1) -a + 36 - 4a +(7a - 26) - 176 = -a + 36 - 4a + 7a - 26 - 176 = 2a - 166 = 2(a - 83)
2) 12x - 4y - 6y -(19x + 21y + 5x -3y) = 12x - 4y - 6y - 19x - 21y - 5x + 3y = -12x - 28y = 2(-6x - 14)
3) 2x( 1 - 3y) = 2x - 6xy
4) (-4 - a) (2 - 1) = -8 + 4 -2a + a = -4 - a