Question

Difference between two numbers is $9$ and difference between their squares is $981$. Lowest of the two numbers is?

• A. $40$
• B. $50$
• C. $55$
• D. $59$

Answer 1

The correct option is B $50$

Let the two numbers be x and y.
According to the question, $x^2-y^2=981$ and $x-y=9$
$\Rightarrow (x-y)(x+y)=981$
$x+y=\frac{981}{9}=109$
$x+y=109$
$x-y=9$
Solving both the equation, $x=59,y=50$
$\therefore$ Lowest number is $50$.