Lời giải:
`2/3-4*(1/2+3/4)`
`=2/3-4*5/4`
`=2/3 - 5`
`=-13/3`
;
;
`(-1/3-5/6)-11-7`
`=-7/6 - 11-7`
`=-73/6 -7`
`=-115/6`
;
;
$\dfrac{\dfrac{3}{4}-\dfrac{3}{5}+\dfrac{3}{7}+\dfrac{3}{11}}{\dfrac{13}{4}-\dfrac{13}{5}+\dfrac{13}{7}+\dfrac{3}{111}}$
$\dfrac{3.(\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{7}+\dfrac{1}{11})}{13.(\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{7}+\dfrac{1}{11})}$
`=3/13`