Pre-Algebra Questions? Define variables, write equations, and solve!

Question

2. Twice the sum of 9 and a number is 84. Find the number.

Answer 1

Let the number is x.

Twice the sum of 9 and a number is 84.

i.e. 2(x + 9) = 84.

Divide each side by 2.

[2(x + 9)]/2 = 84/2

x + 9 = 42

Subtract 9 from each side.

x + 9 - 9 = 42 - 9

x = 33.

Therefore the number is x = 33.