i hope this helps you 7x-3x+18=30 4x=12 x=3

7x - 3(x -6) = 30 Expanding brackets gives.. 7x - 3x + 18 = 30 7x - 3x + 18 - 30 = 30 - 30 4x - 12 = 0 Divide by 4 x - 3 = 0 x = 3