Question

Anna is x years old and her sister, Jane is y years younger

What was the sum of their ages two years ago?
What will be the sum of their ages in 3 years?
How old was anna when Jane was born?

Answer 1

Age of Anna = x years

Age of Jane i.e. Anna's sister = (x-y) years

a, What was the sum of their ages two years ago?

Solution,

Age of Anna two years ago = (x-2) years

Age of Jane two years ago = (x-y-2) years

Sum of their ages = x - 2 + x-y-2 = 2x - y -4

b. What will be the sum of their ages in 3 years?

Solution,

We have,

Present age of Anna = x years

Present age of Jane = (x-y) years

So,

Age of Anna after 3 years = (x+3) years

Age of Jane after 3 years = (x-y+3) years

Therefore,

Sum of their ages in 3 years = (x+3) +(x-y+3) = 2x - y+6

c. How old was Anna when Jane was born?

Solution,

Here,

According to question,

Jane is y years younger than Anna

So, Anna was y years when Jane was born.

[Suppose your age is 10 years and your brothers age is 14 years. You are 4 years younger than your brother. Also, his age was 4 years when you were born.]