Answer :
John's present age is 15 years.
His sister's present age is 10 years.
Step-by-step explanation:
step 1 :
Let,
- Age of sister = x
- Age of john = x+5
step 2 :
The product of their present ages is 150.
⇒ x(x+5) = 150
⇒ x^2 +5x -150 =0
step 3 :
Using factorization method,
product of the roots (-10[tex]\times[/tex]15) = -150
Sum of the roots (-10+15) = 5
∴ The values of x are x=10 and x=-15.
Age cannot be negative.
So, the present age of sister is 10 years.
The present age of John = x+5 = 15 years.