The ratio of the present ages of a son and his father is 1 : 5 and that of his mother and father is 4 : 5. After 2 years the ratio of the age of the son to that of his mother becomes 3 : 10. What is the present age of the father?  Pick.
A) 30 years B) 28 years C) 37 years D) Data inadequate E) None of these
S⁄F = 1⁄5 ⇒ F = 5S   M⁄F = 4⁄5 ⇒ M = 4⁄5 F   S+2/M+2=310   10S + 20 = 30 M + 6 10  + 20= 
<gadget id="calculator">10  + 20</gadget>
<output>30</output>
30 M + 6= 3 × 4⁄5 5S + 6 = 12S + 6   \ 2 S = 14 ⇒ S = 7 years   \ F = 5S = 35 years   Answer None of these
<result>E</result>
The ratio of the present ages of a son and his father is 1 : 5 and that of his mother and father is 4 : 5. After 2 years the ratio of the age of the son to that of his mother becomes 3 : 10. What is the present age of the father?