Question

Twice the sum of a number and 9 equals 7.
Use the variable y for the unknown number.

Answer 1

2(y + 9) = 7 Since it says twice the SUM, you have to do the addition first so the 2 times goes outside the parenthesis.

2y + 18 = 7 Subtract 18 from both sides
2y = -11 Divide both sides by 2
y = -11/2