If 19 equals 10 plus nine, how is
18 composed? 18 equals one plus eight, 18 equals
10 plus eight, 18 equals 10 plus 18.
So we need to choose which answer
is a way of composing or making 18. We could use tens and ones bricks
to help. We can make 18 using a 10 and eight
ones. Our model shows that 18 is equal to
10 plus eight. This is the correct answer.