A bakery made 90 cookies. 28 of them were chocolate chip cookies and 35 of them were raisin cookies. The rest were gingerbread cookies. How many gingerbread cookies did they make?
We’ve drawn a bar model which shows the 90 cookies made by the bakery. We know that 28 of the cookies were chocolate chip, and 35 of the cookies were raisin. And we know the rest of the cookies were gingerbread cookies. We need to work out how many were gingerbread cookies.
This is a two-step problem. First, we need to add together 28 and 35. And then, find the difference between this total and 90. This will tell us how many of the cookies were gingerbread. Let’s add 28 and 35. Eight and five makes 13. We can write the three in the ones place and exchange one 10. Now, we can add the tens. Two and three is five, plus the one we exchanged, makes 6. 28 plus 35 equals 63.
Now, we need to find the difference between 90 and 63. We don’t have anything to subtract three from in the ones column. So, we need to exchange. We need to take one 10. Now, we have eight 10s. And, we can add 10 ones to the ones column. 10 take away three is seven. And eight take away six is two. So, the bakery made 27 gingerbread cookies.
We know the bakery had 90 cookies. 28 of them were chocolate chip, and 35 of them were raisin. First, we added together 28 and 35 which gave us 63. So, we knew that 63 of the cookies were raisin and chocolate chip. Then, we found the difference between 90 and 63 which is 27. This tells us that 27 of the cookies were gingerbread.