Combining like terms
8x + 13x = 42
x=2
4x = x + 3
x=1
-9x + 1 = -80
x=9
10(1 + 3x) = -50
x=-2
-3x = 5x + 8
x=-1
2+ x/4 = -2
x=-16
4(-x + 6) = 12
x=3
-2x + 1 = -4x +9
x=4
x/2 - 10 = -6
x=8
-6(1 - 5x) = 54
x=2
8(1+5x) +5 = 13 +5x
x=0
9x - 7 = -7
x=0
-11-5a=6(5a+4)
x=-1
5(2x+6)=-4(-5-2x)+3x
x=10