Video: Understanding the Relationship Between Addition and Subtraction

Hannah and Anthony made 19 cupcakes. After their dog ate some, there were 15 left. They want to know how many cakes their dog ate. Who is correct?

02:47

Video Transcript

Hannah and Anthony made 19 cupcakes. After their dog ate some, there were 15 left. They want to know how many cakes their dog ate. Who is correct? Hannah says we can solve 15 plus what equals 19. Anthony says we can solve 19 take away 15 equals what.

Let’s see if Hannah is correct. She says we can solve 15 plus what equals 19. In other words, we work out what we add to 15 to get 19. After the dog ate some cakes, there were 15 cakes left. There were 19 cakes to begin with. If we find the difference, this will tell us how many cakes the dog ate.

So let’s start at 15 and count forward until we reach 19. One, two, three, four. The difference is four. This means the dog ate four cakes, according to Hannah. Anthony says we can find the answer if we start at 19 and take away 15. This is because there were 19 cakes to begin with. And after the dog ate some, there were 15 left. So let’s start at 19 and take away 15. 19 take away 10 is nine. Now we need to take away another five. One, two, three, four, five.

Hannah’s answer was four. 15 and four more makes 19. And Anthony’s answer is also four. 19 take away 15 is also four. Both children have worked out that the dog ate four cakes. So the answer to the question who is correct is they are both correct. Hannah and Anthony use different methods to find the answer. But they both got the same answer. They are both correct.

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