The ratio of pencils to erasers is 4: 1 if there are 20 pencils how many erasers are there?

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.

Select the conic section that represents the equation. 3x2 + 3y2 -2x + 4 = 0

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.