Help its ratios please ty no guessing

Cindy uses 1-inch cubes to find the volume of a jewelry box shaped like a rectangular prism. she uses 780 cubes to completely fill the jewelry box with no gaps or overlaps. if the jewelry box is 13 inches long and 5 inches wide, how tall is cindy’s jewelry box?

Solve - pv + 40 < 65 for v solve 7w - 3r = 15 for r

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