Question 3

We will use a variable to represent Salil's age and form an equation.

Step 1 — Define Ages

Let's define Salil's present age. We use a variable for it. Let Salil's present age be $x$ years. His mother's age is three times Salil's age. So, Mother's present age is $3x$ years. Now, let's think about their ages after 5 years. Salil's age will be $x + 5$ years. Mother's age will be $3x + 5$ years.

Step 2 — Form and Solve Equation

Their ages after 5 years add up to 70. We can write this as an equation. $(x + 5) + (3x + 5) = 70$ Combine like terms on the left side. $4x + 10 = 70$ Subtract 10 from both sides. $4x = 70 - 10$ $4x = 60$ Divide both sides by 4. $x = \frac{60}{4}$

$\boxed{x = 15}$

Step 3 — Calculate Present Ages

We found the value of $x$. Salil's present age is $x$ years. So, Salil's present age is 15 years. Mother's present age is $3x$ years. We substitute $x = 15$ into $3x$. $3 \times 15$ $= 45$ So, Mother's present age is 45 years.

Answer

(i) Salil's present age is 15 years. (ii) Mother's present age is 45 years.