"In our class we have 3 books. My teacher says that we need to increase that number of books by 1/8 with each student. If they are 7 students how many books will the class have now?"
Ok there's a quick example but here is how to solve it.
You need to make the 3-fraction friendly and put a one under it
1/3 and now you can multiply 3/1 x 7/8.
Which will now give you 21/8 and simplified it will be 2 5/8
So final answer would be 21/8 = 2 5/8.