X + y = 6
2x + y = 4
Solve the system of equations.

Which expression is equivalent to 8(k + m) − 15(2k + 5m)?

Atriangle has a side lengths of 18cm, 80 cm and 81cm. classify it as acute obtuse or right?

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.