Can u help me on both questions and on this too

If the sales price of a dvd is $20 and the markup is 34%, what is the cost of the dvd?

The perimeter of an equilateral triangle is 4 cm more than the perimeter of a square and the length of a side of the triangle is 8 cm more than the length of a side of the aware. find the length of a side of the equilateral triangle

What is the value of the product (3-2i)(3+2i)?