In a cafeteria 3/10 of the students are eating salads, and 3/5 are eating sandwiches. There are 20 students in the cafeteria. How many students are eating lunches other than salads or sandwiches?

We know that 3/10*20=6 students are eating salads.

We also know that 3/5*20=12 students are eating sandwiches.

Assuming each person only eats one thing, there are 20-12-6=2 students eating lunches other than salads or sandwiches.