Đáp Án+Giải thích các bước giải: 

1. $\frac{3}{4}$.($\frac{1}{4}$: $\frac{7}{8}$) 

= $\frac{3}{4}$.$\frac{2}{7}$ 

= $\frac{3}{14}$ 

2. $\frac{-1}{2}$+ $\frac{5}{6}$+ $\frac{1}{3}$ 

= $\frac{1}{3}$+ $\frac{1}{3}$ 

= $\frac{2}{3}$ 

3. $\frac{5}{4}$-$\frac{1}{2}$+$\frac{-7}{8}$ 

= $\frac{3}{4}$+$\frac{-7}{8}$ 

= $\frac{-1}{8}$ 

4. $\frac{7}{2}$:($\frac{1}{4}$.$\frac{2}{5}$:$\frac{5}{8}$) 

= $\frac{7}{2}$:($\frac{1}{10}$:$\frac{5}{8}$) 

= $\frac{7}{2}$:$\frac{4}{25}$ 

= $\frac{175}{8}$

5. $\frac{1}{2}$.($\frac{4}{3}$+ $\frac{2}{5}$)- $\frac{3}{4}$ 

= $\frac{1}{2}$.$\frac{26}{15}$-$\frac{3}{4}$ 

= $\frac{13}{15}$-$\frac{3}{4}$ 

= $\frac{7}{60}$ 

6. $\frac{-7}{8}$:$\frac{21}{16}$-$\frac{5}{3}$.$\frac{9}{2}$ 

= -$\frac{2}{3}$-$\frac{15}{2}$ 

= -$\frac{49}{6}$ 

Mk Gửi:Xin Ctlhn

`a)`

`3/4 . (1/4 : 7/8)`

`= 3/4 . 2/7`

`= 3/14`

`b)`

`(-1)/2 + 5/6 + 1/3`

`= 1/3 + 1/3`

`= 2/3`

`c)`

`5/4 - 1/2 + (-7)/8`

`= 3/4 + (-7)/8`

`= (-1)/8`

`d)`

`7/2 : (1/4 . 2/5 : 5/8)`

`= 7/2 : (1/10 : 5/8)`

`= 7/2 : 4/25`

`= 175/8`

`e)`

`1/2 . (4/3 + 2/5) - 3/4`

`= 1/2 . 26/15 - 3/4`

`= 13/15 - 3/4`

`= 7/60`

`f)`

`(-7)/8 : 21/16 - 5/3 . 9/2`

`= (-2)/3 - 15/2`

`= (-49)/6`