Question

Father's age is $10$ more than twice age of his son. What is the difference in the age of father and son, if son's age is $21$?

• A. $35$
• B. $31$
• C. $15$
• D. $25$

Answer 1

The correct option is B $31$

Let father's age is $F$ and son's age be $S$.
$F=2S+10$
The equation is in two variable.
Given $S=21$
$F=2S+10=2\times 21+10=52$
$\therefore F-S=52-21=31$