What is the surface area of this right rectangular prism?

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cm²

6n^2-7n-75=0 solve by quadratic formula

If a and b are the measures of two first quadrant angles and sin a = 4/9 and sin b = 2/5 find sin(a+b).

Find the measure of the interior angles of the following regular polygons: a triangle, a quadrilateral, a pentagon, an octagon, a decagon, a 30-gon, a 50-gon, and a 100-gon.