1.) 3(5 - 2x) = -2(6 - 3x) - 10x
15 - 6x = -12 + 6x - 10x
-6x - 6x + 10x = -12 - 15
-2x = -27
x = -27/-2 = 13.5
x = 13.5
2.) 1/4x - 2/5x = 39
-3/20x = 39
x = (39 x 20)/-3 = -260
x = -260
3.) 115 = 20 + 2.5x
2.5x = 115 - 20 = 95
x = 95/2.5 = 38
x = 38
4.) 0.7x - 0.2 = 8.3x + 7.2
8.3x - 0.7x = -0.2 - 7.2 = -7.4
7.6x = -7.4
x = -7.4/7.6 = -37/38
x = -37/38