Correct option is A
Given:
Original salary = Rs. 42,000
New salary = Rs. 57,000
Formula Used:
Percentage Increase=(Original SalaryIncrease)×100
Solution:
Increase = 57,000 − 42,000 = 15,000
Percentage Increase = (4200015000)×100=35.714%
Rounded to 1 decimal place = 35.7%
The percentage increase in his monthly salary is 35.7%.