Hej!
7x + 4 - 2x - 8 = 5x - 4
(2x - 8) - (4x + 8) = 2x - 8 - 4x - 8 =
= -2x - 16
5a(3 + a) - 4(2a - 3a²) =
= 15a + 5a² - 8a + 12a² = 17a² + 7a
(-8b² + 10b - 5) : 5 = -1,6b² + 2b - 1
(3y - 4)(5 - 4y) = 15y - 12y² - 20 + 16y =
= -12y² + 31y - 20
5a(4b - 6) - (4 - a)(2b - 3) =
= 20ab - 30a - (8b - 12 - 2ab + 3a) =
= 20ab - 30a - 8b + 12 + 2ab - 3a =
= 22ab - 33a - 8b + 12