Question

A girls is twice as old as her sister. Four years hence, the product of their ages (in years) will be 160. Find their present ages.

Answer 1

Let the present age of girl bethen, age of her sister

Then, 4 years later, age of girl and her sister’s age be

Then according to question,

So, either

Or

But the age never be negative

Therefore, when then

Hence, the present age of girl be and her sister’s age be