At noon, a tank contained 5 cm of water. After several hours, it contained 3 cm of water. What is the percent decrease of water in the tank?

What is the point-slope equation of a line with slope -5 that contains the point (6,3)

If 1/√5+1/√5+1=p+q√r , find the values of p, q and r

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.