Question:
The product of Ramu's age (in years) five years ago and his age (in years) nice years later is 15. Determine Ramu's present age.
Solution:
Let the present age of Ramu be $x$ years
Then, 9 years later, age of her $=(x+9)$ years
Five years ago, her age $=(x-5)$ years
Then according to question,
$(x-5)(x+9)=15$
$x^{2}+9 x-5 x-45=15$
$x^{2}+4 x-45-15=0$
$x^{2}+4 x-60=0$
$x^{2}+4 x-60=0$
$x^{2}-6 x+10 x-60=0$
$x(x-6)+10(x-6)=0$
$(x-6)(x+10)=0$
So, either
$(x-6)=0$
$x=6$
Or
$(x+10)=0$
$x=-10$
But the age never be negative
Hence, the present age of Ramu be $=6$ years