Question

Amy is 9 years older than her younger sister. if her younger sister is now 1 year old, how many years later will Amy be 4 times as old as her younger sister?​

Answer 1

Answer:-

• Age of Amy's younger sister=1year

☆Amy is 9 years older than her younger sister.

`\\ \sf\longmapsto Age\:of\:Amy=1+9=10years`

Let after x years Amy will be 4times old as her sister.

ATQ

`\\ \sf\longmapsto (1+x)/(9+x)=(1)/(4)`

• Using cross multiplication

`\\ \sf\longmapsto 4(1+x)=1(9+x)`

`\\ \sf\longmapsto 4+4x=9+x`

`\\ \sf\longmapsto 4x-x=9-4`

`\\ \sf\longmapsto 3x=5`

`\\ \sf\longmapsto x=(5)/(3)`

`\\ \sf\longmapsto x=1.6`

`\\ \sf\longmapsto x=2(approx)`