Question 4167
15x+12 = 12x-6 | - 12x on both sides
3x+12 = -6 | - 12 on both sides
3x = -18 | : 3 on both sides
x = -6


You can substitute x with -6 in the original equation to check if -6 is the correct solution. The value on both sides of the equation has to be equal to validate -6 as the correct solution:


15x+12 = 12x-6 
15(-6)+12 = 12(-6)-6
-90 + 12 = -72 - 6
-78 = -78 


-6 is the correct solution.