In the figure below, a tangent and a secant are drawn to a circle from exterior point H. Suppose that HD=31.5 and HG=21. Find HC

Set $r$ is a set of rectangles such that (1) only the grid points shown here are used as vertices, (2) all sides are vertical or horizontal and (3) no two rectangles in the set are congruent. if $r$ contains the maximum possible number of rectangles given these conditions, what fraction of the rectangles in set $r$ are squares? express your answer as a common fraction.

Sally deposited money into a savings account paying 4% simple interest per year. the first year, she earn $75 in interest. how much interest will she earn during the following year?

Yvaries directly as x. y =90 when x=6. find y when x=13