The respective ages of father and his son are 41 and 16 years. In how many years will the father be twice as old as his son ?	Options:
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 + 41 = 2 (x + 16)   x = 41 - 32= 
<gadget id="calculator">41 - 32</gadget>
<output>9</output>
9 years   answer : 9 years
<result>B</result>
The respective ages of father and his son are 41 and 16 years. In how many years will the father be twice as old as his son ?