Four computer desks and three office chairs cost $1110. two desks and five chairs cost $940.

find the cost of a computer desk.

Determine whether the quadrilateral below is a parallelogram. justify/explain your answer (this means back it up! give specific information that supports your decision. writing just "yes" or "no" will result in no credit.)

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.

Given sin28.4=.4756, cos28.4=.8796, and tan28.4=.5407 find the cot of 61.6