I got 1/12th left
I changed all of the fractions to twelfths
4/12
6/12
9/12
16/12
James and Katya ate 10/12 of a sandwich
Ramon ate the last 2/12 and 7/12 of the next sandwich
Sianna ate the other 5/12 and 11/12 of the 3rd sandwich
So that means 1/12 is left
I hope that helps and you get it right