Respuesta :

Answer:

C

Step-by-step explanation:

3(3 + x) = 15 + x

Open bracket

9 + 3x = 15 + x

Collecting like terms

3x - x = 15 - 9

2x = 6

Dividing by 2

x = 6/2

x = 3

Answer:

c

Step-by-step explanation: