Q6 of 80 Page 48

Mary is twice older than her sister. In 5years time, she will be 2 years older than her sister. Find how old are they both now.

Let the present age of Mary’s sister be x years.

Mary is twice older than her sister.


∴ Mary’s present age = 2x years.



According to the given condition,


2x + 5 = x + 5 + 2


2x + 5 = x + 7


⇒ 2x – x = 7 – 5 (Transposing x to LHS and 5 to RHS)


x = 2


The present age of Mary’s sister = x = 2 years.


Mary’s present age = 2x = 2 × 2 = 4 years.


∴ The present ages of Mary and her sister are 4 years and 2


years respectively.


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