Question

Solve for x.
3x - 9 + 4x = 12

A
x = 21

B
x = 3/7

C
x = 3

D
x = -21

Answer 1

Answer:

x = 3

Step-by-step explanation:

Add 9 to both sides of the equation:

3x - 9 + 4x = 12

3x - 9 + 4x + 9 = 12 + 9

3x + 4x = 21

7x = 21

Divide both sides by 7:

7x ÷ 7 = 21 ÷ 7

x = 3

Hope this helps!

Answer 2

Group like terms: 3x - 9 + 4x = 12

Add similar elements: 3x + 4x = 7x

7x - 9 = 12

Add 9 to both sides: 7x - 9 + 9 = 12 + 9

Simplify: 7x = 21

Divide both sides by 7: 7x/7 = 21/7

Simplify: x = 3

The answer is C) x = 3