The twice of sum of the ages of a father and his son is 8 times the age of the son. If the average age of the father and the son is 30 years, what is father's age ?

A 42 yrs

B 45 yrs

C 36 yrs

D 38 yrs

Correct Answer: Option B

Let father's age be x year and son's age be y year.

According to question,

2(x+y) = 8y _______(I)

and (x+y)/2 = 30

=> x+y = 60 years__________(II)

From equation (I) and (II)

8 y = 120

y = 15 years,

Hence x = 45 years.