The respective ages of father and his son are 42 and 16 years. In how many years will the father be twice as old as his son ? Answers.
A) 19 years	B) 9 years	C) 10 years	D) 15 years	E) 12 years
Suppose x years later the father will be twice as old as his son.   x + 42 = 2 (x + 16)   x = 42 - 32= 
<gadget id="calculator">42 - 32</gadget>
<output>10</output>
10 years   answer : 10 years
<result>C</result>
The respective ages of father and his son are 42 and 16 years. In how many years will the father be twice as old as his son ?