Question

10 years ago, Tom was 7 years older than thrice the age of his son. If Tom's present age is $x$ years, then find the present age of his son.

• A. $\frac{x+13}{3}$
• B. $\frac{x-13}{3}$
• C. $\frac{x-13}{6}$
• D. $\frac{x+13}{6}$

Answer 1

The correct option is A $\frac{x+13}{3}$

Let the son's present age be $y$.
Tom's present age $=x$

10 years ago:
Son's age $=y-10$
Tom's age $=x-10$

$x-10=3(y-10)+7$
$x-10-7=3(y-10)$
$x-17=3y-30$
$x-17+30=3y$
$x+13=3y$
$\frac{x+13}{3}=y$

The son's present age is $\frac{x+13}{3}.$