Đáp án:
a) 2/3. x - 4/7 = 1/8
2/3. x = 1/8 + 4/7
2/3. x = 39/56
x = 39/56 : 2/3
x = 117/112
b) 2/7 - 8/9. x = 2/3
8/9. x = 2/7 - 2/3
8/9. x = -8/21
x = -8/21 : 8/9
x = -3/7
c) 4/7 + 5/9: x = 1/5
5/9: x = 1/5 - 4/7
5/9: x = -13/35
x = 5/9 : ( -13/35 )
x = -175/117
d) 2/5 - 2/5. x = 2/4
2/5. x = 2/5 - 2/4
2/5. x = -1/10
x = -1/4
e) (2,8. x - 32) : 2/3 = 90
2,8. x - 32 = 90 . 2/3
2,8. x - 32 = 60
2,8. x = 60 + 32
2,8. x = 92
x = 230/7
f) (4,5 - 3. x). 11/4 = 11/4
4,5 - 3. x = 11/4 : 11/4
4,5 - 3. x = 1
3. x = 4,5 - 1
3. x = 3,5
x = 7/6