Replace * with a monomial in such a way that the trinomial becomes a perfect square. 16y^2+*+81 and 25b^2+70b+*

The volume of a sphere is increased by 6%. calculate the corresponding percentage increased in it area.

Lines b and c are parallel. what is the measure of 2? m2 = 31° m2 = 50° m2 = 120° m2 = 130°

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.