`text{Bài 7}`
`c ) x × 3 1/2 = 4 3/4`
`x × 7/2 = 19/4`
`x = 19/4 : 7/2`
`x = 19/14`
`d ) x : 2 2/3 = 4 1/3`
`x : 8/3 = 13/3`
`x = 13/3 × 8/3`
`x = 104/9`
`text{Bài 8}`
`a ) x + 3/4 = 6 × 3/8`
`x + 3/4 = 18/8`
`x = 18/8 - 3/4`
`x = 3`
`b ) 7/8 : x = 3 - 1/2`
`7/8 : x = 5/2`
`x = 7/8 : 5/2`
`x = 7/20`
`text{Bài 9}`
`a ) 3/2 × 4/5 - x = 2/3`
`6/5 - x = 2/3`
`x = 6/5 - 2/3`
`x = 8/15`
`b ) x × 3 1/3 = 3 1/3 : 4 1/4`
`x × 10/3 = 10/3 : 17/4`
`x × 10/3 = 40/51`
`x = 40/51 : 10/3`
`x = 4/17`
`#dtkc`