x equals 12 because
3x-3= 2x+9
x=12
3(x-1) = 2x+9 Remove the Brackets on the left
3x - 3 = 2x + 9 Add 3 to both sides
3x = 2x + 9 + 3 Collect like terms
3x = 2x + 12 Subtract 2x from both sides.
3x - 2x = 2x-2x + 12
x = 12
