Question

Five years ago, a woman's age was the square of her son's age. ten years later her age will be twice that of her son's age. find the age of the son five years ago.

Answer 1

let the woman's age be x and son's be y 
five years age woman's age = x-5
five years ago son's age= y-5
by data, 
x-5=(y-5)the whole square
solving it we get  x= ysquare-10y+30
woman's age after 10 years= x+10
son's age after 10 years=y+10
by data, 
x+10=2(y+10)
x+10=2y+20
substituting value of x in this equation we get,
ysquare-12y+20=0
y=10 , y= 2

son's age five years ago =x-5
                                        = 10-5=5
                                        x-5= 2-5= -3 (rejected as age cannot be negative)

present age of woman= x+10=2(y+10)
                                         x+10= 2(10+10)
                                          x+10= 40
                                           x=30
i hope uh understood ......... :P :)