(-4) + (-2) - (-12) = -4 -2 + 12 = 6
8 - (+12) - (-15) = 8 -12 + 15 = 11
13 - 23 + 40 = 30
32x + 40y = 8 (4x + 5y)
2500y - 3000 = 500 ( 5y -6)
75x + 50y - 25 = 25 ( 3x + 2y -1)
4 (2x+8) + 7 (7x+4) = 8x + 32 + 49x + 28 = 57 x + 60
7(5x+10) + 10(3,2x - 1,52) = 35x + 70 + 32x - 15,2) = 67x +54,8