What is the simplified form of (81x^4y^9)^1/2

The perimeter of a movie screen is 54 meters. the screen is 18 meters wide. how tall is it?

Marla bought a book for $12.95, a binder for $3.49, and a backpack for $44.99. the sales tax rate is 6%. find the amount of tax and the total she paid for these items

The rectangle shown has a perimeter of 108 cm and the given area. its length is 6 more than five times its width. write and solve a system of equations to find the dimensions of the rectangle.