Question 1154081


Mary is now four times as old as her daughter. Four years ago,the product of their ages was 40. Find their present ages.

If daughter is x 
Mother's age = 4x

4 years ago
daughter's age = x-4
Mother's age = 4x-4

Product of ages (x-4)((4x-4)

(x-4)((4x-4)=40

expand

4x^2-4x-16x+16 =40

4x^2-20x-24=0

x^2-5x-6=0

x^2-6x+x-6=0

x(x-6)+1(x-6)=0

(x-6)(x+1)=0

x=6 or -1

age cannot be negative
x=6

continue