Xin hay nhất nhé tus ^_^
Câu `1:`
$\dfrac{-3}{20}$ `+` $\dfrac{-2}{15}$ `=` $\dfrac{-9}{60}$ `+` $\dfrac{-8}{60}$ `=` $\dfrac{-17}{60}$
`→` Chọn `B`
Câu `2:`
`(-`$\dfrac{5}{13}$`)+(-`$\dfrac{2}{11}$`)+` $\dfrac{5}{13}$ `+(-`$\dfrac{9}{11}$`)`
`=` `(`$\dfrac{-5}{13}$ `+` $\dfrac{5}{13}$`)+(`$\dfrac{-2}{11}$ `+` $\dfrac{-9}{11}$`)`
`=` $\dfrac{-7}{11}$
`→` Chọn `D`
Câu `3:`
`x` `+` $\dfrac{3}{16}$ `=` `-`$\dfrac{5}{24}$
`x` `=` $\dfrac{-5}{24}$ `-` $\dfrac{3}{16}$
`x` `=` $\dfrac{-19}{48}$
`→` Chọn `A`
Câu `4:`
`(7-` $\dfrac{2}{3}$ `-` $\dfrac{1}{4}$`)-(`$\dfrac{4}{3}$ `-` $\dfrac{10}{4}$`)-(`$\dfrac{5}{4}$ `-` $\dfrac{1}{3}$`)`
`=` `7` `-` $\dfrac{2}{3}$ `-` $\dfrac{1}{4}$ `-` $\dfrac{4}{3}$ `+` $\dfrac{10}{4}$ `-` $\dfrac{5}{4}$ `+` $\dfrac{1}{3}$
`=` `7` `+` `(`$\dfrac{1}{3}$ `-` $\dfrac{2}{3}$ `-` $\dfrac{4}{3}$`)+(`$\dfrac{10}{4}$ `-` $\dfrac{1}{4}$ `-` $\dfrac{5}{4}$`)`
`=` `7` `+` $\dfrac{-5}{3}$ `+` `1`
`=` `8` `-` $\dfrac{5}{3}$
`=` $\dfrac{19}{3}$ `=` `6`$\dfrac{1}{3}$
`→` Chọn `B`
