Eighteen years ago, a father was three times as old as his son. Now the father is only twice as old as his son. Then the sum of the present ages of the son and the father is  Choose the correct choice
A) 54.  B) 72  C) 105  D) 108  E) None
Solution   Let the present ages of Father and Son be 2x years and x years respectively.   Then	(2x-18)=3(x-18)   2x-18=3x-54   x=54-18= 
<gadget id="calculator">54-18</gadget>
<output>36</output>
36.   Required sum= (2x+x)   =3x   =3x36   =108 years.   Answer 108
<result>D</result>
Eighteen years ago, a father was three times as old as his son. Now the father is only twice as old as his son. Then the sum of the present ages of the son and the father is