a) 2(5x - 4y) = 10x -8y = -10 - 0.8 = -10,8
b) -x(-x +y) = x^2 - xy = -1 -(-1 * 0,1) = -1 -(-0,1) = -1 + 0,1 = 1,1
c) (150x + 25y - 10)/5 = 30x + 5y - 2 = -30 +0,5 - 2 = -31,5
d) (5x -10y)(5x + 10y) - 100 = 25x^2 +50xy -50xy -100y^2 - 100= 25x^2 - 100y^2 - 100 = -25 - 1 -100 = -126
e) x^2 - (x - 2y)(x + 2y) - (16y^2 - 4x) / 4 = x^2 - x^2 + 2xy -2xy +4y^2 - 4y^2 - x =
-x