18 + 13 = 4x
31 = 4x
x = 31:4
x = 7,75
17x + 26 -3*(4x+3) = 0
17x + 26 - 12x - 9 = 0
5x + 17 = 0
5x = -17
x = -17 : 5
x = -3,4
31/2=2
31=4x
4x=31
x=31/4
18 + 13 = 4x
31 = 4x
x = 31:4
x = 7,75
17x + 26 -3*(4x+3) = 0
17x + 26 - 12x - 9 = 0
5x + 17 = 0
5x = -17
x = -17 : 5
x = -3,4