a, 5x - 8 = 4x - 5 b, 4 - (x - 5) = 5.(x- 3x)
<=> 5x - 4x = 8 - 5 4 - x + 5 = 5x - 15x
x = 3 4 + 5 = 5x - 15x +x
9 = -9x
x = -1
c, 32 - 4(0,5y - 5) = 3y + 2
=> 32 - 2y + 20 = 3y + 2
32 + 20 - 2 = 2y + 3y
=> 50 = 5y => y = 5
d, 2,5 ( y - 1) = 2,5y
=> 2,5y - 2,5 = 2,5y
=> 2,5y - 2,5y = 2,5
=> 0 = 2,5 (vô lý) => ko có y