your answer is x = -3 !!
step 1.) distribute 3 through the parentheses
-12+3x-5x = 7x+15
step 2.) collect like terms
-12-2x = 7x+15
step 3.) move the variable to the left-hand side and change its sign
-2x-7x = 15+12
step 4.) collect like terms
-9x = 15+12
step 5.) add the numbers
-9x = 27
step 6.) divide both sides of the equation by -9
so x would equal -3 !! :D
