Bài 1:
a) 2/3 + 1/2 - 3/5
= 7/6 - 3/5
= 17/30
b) 3/7 + 4/7 . 5/2 - 50%
= 3/7 + 10/7 - 1/2
= 13/7 - 1/2
= 19/14
c) 2$\frac{1}{3}$ : (75% - 1,25) - (-2/3)²
= 7/3 : (3/4 - 5/4) - 4/9
= 7/3 : (-1/2) - 4/9
= -14/3 - 4/9
= -46/9
Bài 2:
a) x + 5/4 = 3/20
x = 3/20 - 5/4
x = -11/10
Vậy x = -11/10
b) (5/12 - 3/4 . x) . (-1$\frac{3}{5}$) = -7,2 . 50%
(5/12 - 3/4 . x) . (-8/5) = -7,2 . 1/2
(5/12 - 3/4 . x) . (-8/5) = -18/5
5/12 - 3/4 . x = -18/5 : (-8/5)
5/12 - 3/4 . x = 9/4
3/4 . x = 5/12 - 9/4
3/4 . x = -11/6
x = -11/6 : 3/4
x = -22/9
Vậy x = -22/9
