Learning from Teacher Tube

After watching the video, solve the following problem by Factoring.

An architect created a proposal for a fountain. Each level (except the top one) is an X formed by cubes. The number of cubes in each of the four parts of the X is one less than the one on the level below. A formula for the total number of cubes, c , in the fountain is given by the equation,

c = 2n^2 - n where n is the number of levels in the fountain.

How may levels would a fountain of 66 cubes have?