You are at a trade show where you are selling baseball cards for $4 a car and buyng baseball cards for $6 a card. If you started the day with $200, how much money do you have at the end of the day if you sold c baseball cards and bought b baseball cards?

What is the size of the matrix resulting from

Calculate the missing value. round the answer to on decimal place. start with 70, increase it by 21%, and end up with

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.