Giải thích các bước giải:
`a)` `{-10}/13+5/17-3/13+12/17-11/20`
`=({-10}/13-3/13)+(5/17+12/17)-10/20`
`=(-1)+1-10/20`
`=-11/20`
`b)` `3/4+{-5}/6-11/{-12}`
`={9+(-10)+11}/12`
`=10/12`
`=5/6`
`c)` `(13 4/9+2 1/9)-3 4/9`
`=(13 4/9+3 4/9)-2 1/9`
`=10+2 1/9`
`=12 1/9`
`d)` `1,25:15/20+(25%-5/6):4 3/2`
`=5/4. 4/3+(1/4-5/6). 3/14`
`=5/3+7/12. 3/14`
`=5/3+{-1}/8`
`=37/24`
