Question

Use the model to find the missing number in the pair of equivalent expressions. 15 + 9 = ?(5 + 3) What number is missing from the expression?

Answer 1

Let:

x = Missing number

15 + 9 = x(5 + 3)

24 = 5x + 3x

24 = 8x

Solving for x:

24/8 = x

3 = x

x = 3