Bonsoir,
c) 8 + 4 (1/2x + 2/5) = - 8/5 (- 5/8x - 1)
8 + 4/2x + 8/5 = 40/40x + 8/5
4/2x - x = 8/5 - 8/5 - 8
2x - x = - 8
x = - 8
d) 3/4 - 1/2 (- 4x + 2/7) = 6/7 - 1/4x
3/4 + 4/2x - 2/14 = 6/7 - 1/4x
4/2x + 1/4x = 6/7 - 3/4 + 2/14
8/4x + 1/4x = 24/28 - 21/28 + 4/28
9/4x = 7/28
9/4x = 1/4
2,25x = 0,25
x = 0,25/2,25