$Đáp$ $án$ $+$ $Giải$ $thích$ $các$ $bước$ $giải$ $:$

`tt\color{#36648B}{\text{ϟҡıṅɢṃåṭһṡ ⚡︎}`

$a)$ `( 17/5 - 7/3 ) xx 35/8`

`= ( 51/15 - 35/15 ) xx 35/8`

`= 16/15 xx 35/8`

`= 14/3`

`-----`

$b)$ `( 17/3 - 7/4 ) xx 12/5`

`= ( 68/12 - 21/12 ) xx 12/5`

`= 47/12 xx 12/5`

`= 47/5`

`-----`

$c)$ `8/15 : 4/5 - 2/5`

`= 8/15 xx 5/4 - 2/5`

`= 2/3 - 2/5`

`= 10/15 - 6/15`

`= 4/15`