The students in mrs. mandel’s class need to choose two class
representatives from six nominated students. how many different
combinations of class representatives are possible?

Do you know the Combination Formula? If Not it is (n!)/r!(n - r)!
I think n would equal 6, and r would equal 2. So it would be 6!/2!(4!)
I believe you can do this yourself now that I've given you an equation.

Ican't do any of the other stuff, but i can get you started. the answer, i believe, is $2.50.