Does increase in math mean multiply

Yes.

Increase can also mean addition!

so what is it?

Check your text -- the answers are always in your text, whether online or in print.

The problem is If Fran's recipe calls for 2 1/2 cups of sugar and she increases it by 2/5 of a cup how much sugar does she use?

2 2/10
2 3/7
2 4/9
2 9/10

Ok ill check my text

You have two numbers. Add them!

https://www.mathsisfun.com/fractions_addition.html

I tried the problem but i didn't get any of the answers i got 14/10 wich would be something different

2 1/2 + 2/5 ?????

5/2 + 2/5

25/10 + 4/10 = 29/10 = 2 9/10