3 (6+3n) = 5n + 18 + 3n

n = 0

Step-by-step explanation:

Multiply parenthesis by 3 and get:

1.) 18 + 9n = 5n + 18 + 3n

Then cancel the equal terms:

9n = 5n + 3n

Collect like terms:

9n = 8n

Move variable to the left:

9n - 8n = 0

n + 0

Plugin the value of 0 into x:

3 (6 + 3 x 0) = 18

5 x 0 + 3 x 0 + 18 = 18

*If the plugged in value have the same result than the answer is correct because 18 + 18.