Please help me in this:
A=(-3;0]and B=(-1;2) calculate A-B and B-A

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

An arithmetic series a consists of consecutive integers that are multiples of 4 what is the sum of the first 9 terms of this sequence if the first term is 0

Due to financial difficulties the owner of 4 skateboard stores is going to close 2 of his stores. based on the money earned at each store, which two stores should remain open?