Question

The salary of an officer is increased by $25\%$. By what per cent should the new salary be decreased to restore the original salary?

• A. $5\%$
• B. $10\%$
• C. $15\%$
• D. $20\%$

Answer 1

The correct option is D $20\%$

Let the original salary be $x$

Given that the salary is increased by $25\%$

Therefore, the increased salary is $x+0.25x=1.25x$

To restore the original salary, let the salary be decreased by $y\%$

Therefore, $1.25x-0.01y\left(1.25x\right)=x$

$⟹1.25-0.0125y=1$

$⟹0.0125y=0.25$

$⟹y=20\%$

Therefore, to restore the original salary, the salary should be decreased by $20\%$