Question 239836
LET THE MAN'S AGE=4X
LET THE SON'S AGE-X
(4X+4)(X+4)=520
4X^2+4X+16X+16=520
4X^2+20X+16-520=0
4X^2+20X-504=0
4(X^2+5X-126)=0
4(X-9)(X+14)=0
X-9=0
X=9 AGE OF THE SON.
4*9=36 AGE OF THE DAD.
PROOF:
(4*9+4)(9+4)=520
(36+4)(13)=520
40*13=520