-15x +12 +3. (2x-6) = 3x- (21x-1)+2-15x +12 + 6x - 18 = 3x - 21x +1 +2-9x - 6= -18x +3-9x + 18x= 3+69x= 9x= 9/9x=1
-15+12+3(2x-6) = 3x-(21x-1)+2-15+12+6x-18 = 3x-21x+1+26x-21 = -18x+36x+18x = 3+2124x = 24x = 24/24 = 1