the equation will be 2x + 7 = 3x
subtract 2x from bothsides, you get 7 = x
so x is equal to 7
EDITED
sorry, i didnt read the sum part, so my answer is considered wrong ahaha
2(x+7) equals 3x
distribute, you get 2x+14=3x
then subtract 2x,
the answer for x is 14