Delhi Police Constable Exam Model Paper 3

Given
,A college decide to increase its teacher salary by 30%
But due to corona virus pandemic disease the college later decide to decrease 20% in salary of its employees.
Formula:
If x% increase of any value, then Increased value = Actual value $\times \frac{\left(100+\mathit{x}\right)}{100}$
If y% decrease of any value, then
Decreased value = Actual Value × (100 – x)/100
Calculation:
Let salary of the teacher be Rs 100xIncreased salary of the teacher = 100x × (130/100) = 130x
After corona virus salary of the teacher = 130x × (80/100) = 104x
Salary increased by = 104x – 100x = 4x
∴ Salary increased by = (4x/100x) × 100 = 4%
Smart Trick
Net increase = x + y + (xy)/ $100=30+\left(-20\right)+\frac{\left(30\times -20\right)}{100}=30-20-6=+4\%$