Bài 1: (2 điểm) Thực hiện phép tính (Tính hợp lý nếu có thể) a) $2\frac{1}{9}$ -$\frac{1}{3}$: $\frac{3}{7}$  b) $\frac{7}{19}$. $\frac{8}{11}$+ $\frac{3}{11}$. $\frac{7}{19}$+ $\frac{-12}{19}$  c) $20\frac{8}{23}$ - $(5\frac{7}{32}$ +$14 \frac{8}{23})$  d) 75% - $1\frac{1}{2}$+ 0,5: $\frac{5}{12}$- $(-\frac{1}{2})^2$ 

Giải thích các bước giải:

`a) 2 1/9 - 1/3 : 3/7`

`= 19/9 - 1/3 . 7/3`

`= 19/9 - 7/9`

`= 12/9`

`-----`

`b) 7/19 . 8/11 + 3/11 . 7/19 + (-12)/19`

`= 7/19 . ( 8/11 + 3/11 ) + (-12)/19`

`= 7/19 . 1 + (-12)/19`

`= 7/19 + (-12)/19`

`= -5/19`

`-----`

`c) 20 8/23 - ( 5 7/32 + 14 8/23 )`

`= 468/23 - ( 167/32 + 330/23)`

`=468/23-167/32-330/23`

`=(468/23-330/23)-167/32`

`=6 - 167/32`

`= 192/32 - 167/32`

`= 25/32`

`-----`

`d) 75% - 1 1/2 + 0,5 : 5/12 - ( -1/2)^2`

`= 3/4 - 3/2 + 1/2 . 12/5 - 1/4`

`= 3/4 - 6/4 + 6/5 - 1/4`

`= ( 3/4 - 6/4 - 1/4 ) + 6/5`

`= -1 + 6/5`

`= -5/5 + 6/5`

`= 1/5`

`#By`