The table shows the normal price of some items of school uniform. Christopher wants to buy two shirts, one pair of trousers, and one blazer. One store is offering a discount on this combination of items if bought today. Today, two shirts, one pair of trousers, and one blazer would cost 45 pounds. Part a), how much money will Christopher save by buying the items today?
There is also part b, which we’ll come onto in a bit. Well the first thing we want to do is actually work out what the normal cost would be before the offer. And to do that, what I’m going to do is actually add up the cost of each of the items that he wants to buy. So first of all, he wants to buy two shirts. And we can see that each shirt costs eight pound 90. So what we’re gonna do is put that on twice onto our column addition. He then wants to buy one pair of trousers, so trousers cost 11 pound 40. So again I’ve put this on our column addition. And then finally, he wanted one blazer, and a blazer cost 19 pounds 50. So again I’ve added that to our column addition. And we’ve actually got it completely set up here. The key thing here is to actually make sure that the price values are actually all lined up. And the way to do that really is by actually making sure that the decimal points are lined up as we have here.
So now what we do is we actually add up each of the values. So first of all, we’ve got zero plus zero plus zero plus zero, which is just zero. Nice and easy! Next, we have nine add nine, which is 18, add another four is 22, add five is 27. So therefore, we’re gonna put the seven in the ten pence column and carry the two into the pounds column. So now we’ve got eight add eight, which is 16, add one is 17, add nine is 26, then add the two that we carried is 28. So we put eight in the pounds column and then carry a two. And now we’ve got one, two, and then add the two that we carried, it gives us four. So then we actually put the four into the ten pounds column. And we’ve got the total price for the normal cost of buying the items before the deal: it’s going to be 48 pounds 70.
So now what we want to do is actually work out how much money Christopher will save by buying the items today. And to calculate his saving, what we’re gonna do is the normal cost minus the deal cost. So this is gonna be equal to 48 pounds 70, and that’s because 48 pound 70 is our normal cost, minus 45 pounds, because this is the offer price cause it says that today two shirts, one pair, of trousers and one blazer would cost 45 pounds. So that gives us three pounds 70. And we can actually get that with a mental method, cause what we could do is actually count up from 45 pounds, cause we can go got 45 pounds well you need to add three to get to 48 pounds, and then add 70 p to get to 48 pounds 70. So that’s three pounds 70.
You could have also used column subtraction, which I’ve set up here. So you’d have zero minus zero, which is just zero, seven minus zero is seven, eight minus five, which is three, and finally we’ve got zero, because as we said if we take four away from four, you just gonna be left with zero. So this gives us the same price as before, so the same saving which is three pounds 70. So therefore, we can say that Christopher will save, by buying the items today using the offer, three pounds 70.
So now for part b, we actually have a bit of extra information. Christopher takes 73 minutes to drive to the shop. He arrived at 9:45 pm. Part b) at what time did Christopher begin his journey?
Well the first thing we want to do is actually have a look at the time that Christopher takes, which is 73 minutes. And we actually want to convert this into hours and minutes cause that way it’s gonna make it much easier for us to actually see when he began his journey. Well a piece of information that’s gonna help us is that one hour is equal to 60 minutes. So therefore, what we can do is actually break down our 73 minutes to 60 plus 13, because we want to do that because we know that there are 60 minutes in an hour. So therefore, we can say that there are actually one hour and 13 minutes in 73 minutes. So now what we want to do is actually to subtract this, so this 73 minutes which we know is one hour 13 minutes, from our 9:45 pm to get the time that Christopher began his journey.
Well first of all, we’re gonna do the most straightforward part which is actually to subtract one hour from 9:45 pm. And if we subtract one hour from that, we’re gonna get to 8:45 pm. And then we’re gonna subtract the 13 minutes from the one hour 13 minutes. Well if we think about 45, cause we’re only interested in the minutes here, minus 13, well first of all we have five minus three, which is two, and then we’ve got four minus one, which is three. So we can say that 45 minus 13 is 32. So therefore we can say that 8:32 pm would be our start time. So therefore, we can say that if Christopher takes 73 minutes to drive to the shop and he arrived there at 9:45 pm, the time that he began his journey is 8:32 pm. And we can double check that by adding on the hour and 13 that we’d actually calculated. So if you add on an hour to 8:32, well you get to 9:32. Then add on 13 minutes, well if we add on 10 minutes, we get to 9:42, add on another three minutes takes us to our 9:45 pm. So therefore, our answer is correct.