Question

After five years, the age of a father will be thrice the age of his son. Five years ago, he was seven times old as his son was. What is father's present age?

• A. $35$ years
• B. $40$ years
• C. $45$ years
• D. $50$ years

Answer 1

Answer: (B)

$40$ years

Let Father's age be F and Son's age be S
then 5 years ago,
$F-5=7(S-5)$
$F=7S-30$
5 years hence,
$F+5=3(S+5)$
$F=3S+10$
Thus, $7S-30=3S+10$
$4S=40$ or $S=10$
and, $F=40$ years
Father's age is 40 years