A model with 3 rows of 5 squares and 3 rows of 3 squares.

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

To solve the equation \( 15 + 9 = ?(5 + 3) \), we first need to evaluate both sides.

1. Calculate the left side: \[ 15 + 9 = 24 \]

2. Now evaluate the right side expression: \[ 5 + 3 = 8 \]

3. We can now set up the equation since we know the left side equals 24: \[ 24 = ? \cdot 8 \]

4. To find the missing number, divide both sides by 8: \[ ? = \frac{24}{8} = 3 \]

Thus, the missing number in the expression is \( 3 \).

So, the final answer is: \[ \boxed{3} \]