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?

Answer 1

Let the original salary = Rs.100 

Then, 

After increment of 25% = 100 (1 + 25/100) 

= 100 (125/100) 

= Rs.125 

Now, 

To restore the original salary, 

Let the new salary decreased by Z% 

∴ 125(1 – Z/100) = 100 

⇒ (1 – Z/100) = 100/125 

⇒ (1 – Z/100) = 4/5 

⇒ Z/100 = 1/5 [1 – 4/5 = 1/5] 

⇒ Z = 100/5 

⇒ Z = 20%