Question

Ravi's age is double Ranu's age. The product of their ages in years is 72. How old is Ranu?

Please show work.

Answer 1

Let A be Ravi's age and let B be Ranu's age, we have:

$A=2B \\ AB=72$

To solve this, we can jsut sub A for 2B and solve for B (which is good since the problem asks for Ranu's age, which is B), so:

$2B*B=72 \implies\\ 2B^2=72 \implies\\ B^2=36 \implies\\ B=6$

We only had to consider the positive solution since age cannot be negative. With that we know that Ranu's age is 6 and Ravi's age is 12.