Verify associativity of addition of rational i.e., `(x+y)+z=x+(y+z),` when:
(i)`x=1/2, y=2/3,\ z=-1/5`

(ii)`x=(-2)/5, y=4/3,\ z=\ (-7)/(10)`

Explanation

(i)`x=1/2, y=2/3,\ z=-1/5`
`=>[1/2+2/3]+(-1/5)=(1/2)+[2/3-1/5]`
`=>7/6-1/5=-1/2+7/5`
`=>(35-6)/(30)=(15+14)/(30)`
`=>29/30=29/30`

(ii)`x=(-2)/5, y=4/3,\ z=\ (-7)/(10)`
`=>[-2/5+4/3]+(-7/10)=(-2/5)+[4/3-7/10]`
`=>14/15-7/10=-12/30+19/30`
`=>(28-21)/(30)=(-12+19)/(30)`
`=>7/30=7/30`
Hence verified.