One is the integral of e^x times cos x.
Use integration by parts.
The correct answer is x=12
5x+2y = 20
For every hardcover book (x) you will be charged 5$.
For every paperback book (y) you will be charged 2$.
The amount of both types of books you buy has to be under or equal to 20$
129 degrees you just add DCE and ECF together
