Đáp án:
$\text{a)}$ `2/3`
$\text{b)}$ `4/3`
Giải thích các bước giải:
$\text{a)}$ `5/12` $\text{x}$ `2/3` + `2/3` $\text{x}$ `7/12`
$=$ `2/3` $\text{x}$ `(` `5/12` `+` `7/12` `)`
`=` `2/3` $\text{x}$ `1`
`=` `2/3`
$\text{b)}$ `13/8` `:` `3/4` `-` `5/8` `:` `3/4`
`=` `(``13/8` `-` `5/8``)` `:` `3/4`
`=` `1` `:` `3/4`
`=` `4/3`