### Home > MC1 > Chapter 9 > Lesson 9.3.1 > Problem 9-128

9-128.

Add *x* and *y* to get the sum. Multiply *x* and *y* to get the product.

Follow the pattern shown above right.

5 + *y* = 5 + *a*

What is *y*?

The product is 5*a*.

0.99 − 0.90 = 0.09

9-128.

Add *x* and *y* to get the sum. Multiply *x* and *y* to get the product.

Follow the pattern shown above right.

5 + *y* = 5 + *a*

What is *y*?

The product is 5*a*.

0.99 − 0.90 = 0.09