Please Help! A tower stands on a 20-degree slope. From a point 45 m directly up the slope. The angle of elevation of the top of the tower is 10 degrees. How tall is the tower?

The answer is  2x³ + 12x² + 10x - 24

(2x² + 6x - 8)(x + 3) = x(2x² + 6x - 8) + 3(2x² + 6x - 8) =
                                = 2x³ + 6x² - 8x + 6x² + 18x - 24 =
                                = 2x³ + (6x² + 6x²) + (-8x + 18x) - 24 =
                                = 2x³ + 12x² + 10x - 24