Option A) Mahesh, ₹80
Money earned by Mahesh from 1 smartphone = ₹320
Money earned by Mahesh from selling 4 smartphones = ₹320 × 4 = ₹1280
Money earned by Suresh from 1 smartphone = ₹400
Money earned by Suresh from selling 3 smartphones = ₹400 × 3 = ₹1200
Clearly Mahesh earned more on that day as 1280 > 1200.
Difference = ₹1280 - ₹1200