1.
0.625X=8分之7X-50
5X/8 = 7X/8 - 50
50 = (7/8 - 5/8)x
50 = (1/4)x
x=200
2.
4分之3X-6=5分之3（X+6）
3X/4 - 6 = 3(X+6)/5
0.75x - 6 = 0.6x + 1.2
(0.75 - 0.6)x = 1.2 + 6
0.15x = 7.2
x = 48
3.
5分之4X-16=3分之2（X-12）
4x/5 - 16 = 2(x-12)/3
4x/5 - 16 = 2x/3 - 4
(4/5 - 2/3)x = -4 + 16
(2/15)x = 12
x = 90
4.
0,25X=0.2（X+20）
0.25x - 0.2x = 0.2×20
0.05x = 4
x = 80