First, you need to get rid of the parenthesis by distributing:
3(x + 1) = 3x + 3
So 7x - 16 = 3x + 3 - 3
7x - 16 = 3x
Subtract both sides by 3x and you'll get:
4x -16 = 0
Now, add 16 to both sides and you'll get:
4x = 16
Divide both sides by 4:
x = 4
