First, expand the term in parenthesis on the left side of the equation by multiplying each term within the parenthesis by the term outside the parenthesis:
#color(red)(-6)(-7x - 6) = 8x + 36#
#(color(red)(-6) * -7x) + (color(red)(-6) * - 6) = 8x + 36#
#42x + 36 = 8x + 36#
Next, subtract #color(red)(36)# and #color(blue)(8x)# from each side of the equation to isolate the #x# term while keeping the equation balanced:
#-color(blue)(8x) + 42x + 36 - color(red)(36) = -color(blue)(8x) + 8x + 36 - color(red)(36)#
#(-color(blue)(8) + 42)x + 0 = 0 + 0#
#34x = 0#
Now, divide each side of the equation by #color(red)(34)# to solve for #x# while keeping the equation balanced:
#(34x)/color(red)(34) = 0/color(red)(34)#
#(color(red)(cancel(color(black)(34)))x)/cancel(color(red)(34)) = 0#
#x = 0#