Calculating Marbles After Combining and Giving Away

In a small classroom, each student has a different amount of marbles. The number of marbles for each student can be represented as the following rational numbers:

Student A: 3.5, Student B: -1.25, Student C: 0.75, Student D: 2.0.

If Students A and C combine their marbles and give away 2 marbles to Student B, how many marbles does Student B have in total?