Disagree. Find out the original price of each piece of clothing and how much you have earned or lost, and then compare it.

Calculation process: the original price of the clothes that make money is 240÷( 1+20%)=200 (yuan), so the clothes earn: 240-200=40 (yuan).

The original price of the clothes that lost money was 240÷( 1-20%)=300 yuan, so the clothes lost money: 300-240=60 yuan.

So the boss lost: 60-40=20 (yuan)