Đáp án:

 

Giải thích các bước giải:

`a)`

` 3/7 * ( - 8/9 ) * ( - 7/8 ) `

`= (3 * 8 * 7)/(7 * 9 * 8) `

`= 3/9 `

`= 1/3 `

``

`b)`

` ( - 1/3 )^2 * ( - 18/4 ) `

`= 1/9 * ( - 18/4 ) `

`= - ( 1 * 18 )/(9 * 4 ) `

`= - 2/4 `

`= - 1/2 `

``

`c)`

` - 1/2 : ( - 2/3 ) : ( - 3/4 ) `

`= - 1/2 * ( - 3/2 ) * ( - 4/3 ) `

`= - ( 1 * 3 * 4 )/(2 * 2 * 3 ) `

`= - ( 1 * 3 * 4 )/(4 * 3 ) `

`= - 1 `

``

`d)`

` - 4/3 * 9/8 : ( - 5/2 ) * 4/25 `

`= - 4/3 * 9/8 * ( - 2/5 ) * 4/25 `

`= ( 4 * 9 * 2 * 4 )/(3 * 8 * 5 * 25 ) `

`= 288/3000 `

`= 12/125`