Father is aged square times more than his son john. After 3 years, he would be three times of John's age. what would be the age of John's Father after 15 years ?
Choices: A) 18 B) 36 C) 40 D) 57 E) 45
Let Father's age be J and John's' age be D...   Given J   + 3= 
<gadget id="calculator">  + 3</gadget>
<output>3</output>
3(D + 3 )=&gt; J - 6 = 3D -&gt; Eq1.   Given J-6 = (D-6)^2 --&gt; Eq 2..   sub J-6 value in eq 2... 3D = D^2 - 12D + 36.   0 = D^2 - 15D + 36 =&gt; D = 12 or D = 3.   When D = 12 we get from eq 1... J+3 = 45 =&gt; J =42..   When D = 3 ..we get from eq 1.. J+3 = 18 =&gt; J = 15...   In the above options only 42 exits..   IMO option 57 is correct answer..
<result>D</result>
Father is aged square times more than his son john. After 3 years, he would be three times of John's age. what would be the age of John's Father after 15 years ?