Samuel orders four DVDs from an online music store. Each DVD costs $10.00. He has a 20% discount code, and sale tax is 6.75%. What is the total cost of his order

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

When the solutions to each of the two equations below are graphed in the xy-coordinate plane, the graphs of the solutions intersect at two places. write the y-cordninates of the points of intersection in the boxes below in order from smallest to largest. y=2x y=x^2-3

How to simply and write the answer n a whole number