Marlo is painting his bedroom walls. The room is rectangular in shape with width w and length 2. Marlo knows he can find the area A of the four walls to be painted (not accounting for doors or windows) using the formula A = 21h + 2wh, where h is the height of each wall that is painted. The label on the paint can gives the area that the paint is expected to cover but Marlo is unsure how high up each of the walls he can paint. Which of these shows the formula rewritten so that it has been solved for h?