Question 998811
Let son be y years
father be x years

x= y^2+4

x+4y =64

substitute x

y^2+4+4y=64

y^2+4y-60=0

y^2+10y-6y+60=0

y(y+10)-6(y+10)=0

(y+10)(y-6)=0

y= 6 OR -10

discard -10

son's age = 6 years

Father's age = 40 years