Explanation:
Ethan sold 2/3 gallon of lemonade.
Kayla sold some lemonade too.
Together they sold 1 1/4 gallons.
Subtract 2/3 from 1 1/4 as follows :

So, Kayla sold 7/12 gallons of lemonade.
As 2/3 is more than 7/12, it means Ethan sold more lemonade.

It means Eathn sold 1/12 more lemonade.