Asubmarine must descend at an average rate of at least 10 feet per minute for 5 minutes. the table shows how many feet the submarine descends in the first 4 minutes. how many feet must the submarine descend in the fifth minute?

Name each raycalculation tip: in ray "ab", a is the endpoint of the ray.

60 2(x + 2) in the diagram, gef and hef are congruent. what is the value of x?

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.