`9/4 + 1/3 - 2/5`
`= 135/60 + 20/60 - 24/60`
`= 155/60 - 24/60`
`= 131/60`
_______________________________
`7/9 + 2/3 : 4/9`
`= 7/9 + 3/2`
`= 14/18 + 27/18`
`= 41/18`
_______________________________
`3/8 + 7/5 xx 3/10`
`= 3/8 + 21/50`
`= 75/200 + 84/200`
`= 159/200`
_______________________________
`1/5 : 2`
`= 1/5 xx 1/2`
`= 1/10`
