Solve for the variable
7 (x + 1) + 4 (2x - 3) = 40

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.

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,

x = 3

He is right i did this thing before