One way to make addition easier is to use addition facts that we already know.

Let us try to find by first making 10.

We need to add 3 more to 7 to make 10. So move 3 green squares over.

Now we have the same number of squares, but there are 10 in the first ten-frame, and 5 in the second.

So is the same as which makes 15.

Now you have a go. What is ?