First you must expand the brackets, 7x + 7 + 8x -12 = 40 Then take your numbers (without the x's) and put them on the opposite side of the equals sign. Remember once you swap the sides a + will turn into a - and a - will turn to a + 7x + 8x = 40 -7 + 12 Then simplify, 15x = 45 Finaly divide 45 by 15, (Sadly there's no divide sign on my phone) 15 x 3 = 45 This means,
<span><span>First distribute the numbers outside the parentheses - 7x
+ 7 + 8x - 12 = 40 - and then combine the like numbers - 15x - 5 = 40. To
isolate x, add 5 to both sides, so that 15x = 45. Solve for x by dividing both sides by 15. The answer is x =
3.</span></span>
