Bài 1. (2,0 điểm) Thực hiện phép tính (tính hợp lí nếu có thể). a) $\frac{1}{2}$ - $\frac{7}{10}$ + $\frac{-1}{5}$  b) $2: \frac{11}{5}$ - ($\frac{1}{3}$ - $\frac{1}{11}$ ) c) $\frac{5}{11}$ . ($\frac{3}{5}$ - $\frac{22}{7}$ ) + ($\frac{-14}{11}$ - $\frac{4}{7}$ )

Bài `1:`

`a)` `1/2 - 7/10 + (-1)/5`

`=5/10 - 7/10 + (-2)/10`

`=(-4)/10`

`=(-2)/5`

`b)` `2 : 11/5 - (1/3 - 1/11)`

`=2 . 5/11 - 1/3 + 1/11`

`=10/11-1/3 + 1/11`

`=30/33 - 11/33 + 3/11`

`=2`

`c)` `5/11.(3/5-22/7)+(-14/11-4/7)`

`= 5/11 . 3/5 - 5/11 . 22/7 +(-14/11-4/7)`

`= 3/11-10/7-14/11-4/7`

`= (3/11-14/11)+(-10/7-4/7)`

`= -1-2`

`= -3`