First, group and combine like terms on the left side of the equation:
#7x - 5x + 6x - 7 - 18 = 3x#
#(7 - 5 + 6)x + (-7 - 18) = 3x#
#8x + (-25) = 3x#
#8x - 25 = 3x#
Next, add #color(red)(25)# and subtract #color(blue)(3x)# from each side of the equation to isolate the #x# term while keeping the equation balanced:
#-color(blue)(3x) + 8x - 25 + color(red)(25) = -color(blue)(3x) + 3x + color(red)(25)#
#(-color(blue)(3) + 8)x - 0 = 0 + 25#
#5x = 25#
Now, divide each side of the equation by #color(red)(5)# to solve for #x# while keeping the equation balanced:
#(5x)/color(red)(5) = 25/color(red)(5)#
#(color(red)(cancel(color(black)(5)))x)/cancel(color(red)(5)) = 5#
#x = 5#
