Câu `1`:
`a) -2,125 : ( - 3 23/24 )`
`=` $\dfrac{-212,5}{100}$ `: (- 85/24 )`
`=` $\dfrac{-212,5}{100}$ `. ( - 24/85 )`
`= 5100/8500`
`= 3/5`
`b)` $\dfrac{87,5\%}{-1 \dfrac{5}{16} }$
`=`$\dfrac{\dfrac{875}{1000}}{ \dfrac{-21}{16} }$
`= 875/1000 : (-21/16)`
`= 875/1000 . (- 16/21)`
`= - 14000/21000`
`= - 2/3`
$#Dyn.Shun$
$@Shun$~