First of all, we have to expand the brackets.
8 x 12 - 3x = 5x - 10 + 3
Then, we have to put all the x terms on one side. We do that by adding 3x to both sides to get rid of that -3x on the left.
8 x 12 = 8x - 10 + 3
Now we have to get x on its own, so if we do the numbers first to make it easier:
96 = 8x - 7
Now add seven to both sides: 103 = 8x
Then divide both sides by eight to find x. This leaves us with 12.875.
Hope I helped!