12.Fifteen years from now Ravi’s age will be four times his present age. What is Ravi’s present age?

Let the present age of Ravi be x years.
After 15 years, his age will be = (x + 15) years

As per the conditions given, we have

\(\Rightarrow\) x + 15 = 4x

\(\Rightarrow\) 15 = 4x – x (transposing x to RHS)

\(\Rightarrow\) 15 = 3x

\(\Rightarrow\)15 ÷ 3 = x (transposing 3 to LHS)

\(\Rightarrow\) x = 5

Hence, the present age of Ravi = 5 years.