Question

Solve the equation using mental math.

7 + r = 15

Answer 1

`\displaystyle 8 = r`

Explanation:

7 + r = 15

- 7 - 7

________

`\displaystyle r = 8`

I am joyous to assist you anytime.

Answer 2

r = 8

Explanation:

7 + 8 = 15

so r = 8!