The first pair: 240 is 80% of the selling price, and 240 divided by 80%=300 yuan.

Second pair: 240 is the selling price 120%, and 240 divided by 120%=200 yuan.

There are two ways to do this:

(1) The first pair of losses is 300-240=60 yuan.

The second pair earns 240-200=40 yuan.

60 yuan is bigger than 40 yuan.

Lost 20

②300+200=500 yuan 240+240=480 yuan.

500 yuan is bigger than 480 yuan.

Lost 20

But if there is no percentage sign after 20, it means that you don't make a profit or lose money.