Your classmate is starting a new fitness program. he is planning to ride his bicycle 45 minutes every day. he burns 10 calories per minute bicycling at 11mph and 13.75 calories per minute bicycling at 15 mph. how long should he bicycle at each speed to burn 600 calories per hour?

Which equation expression the relationship between the number of boxes b and the number of cans c and the proportion is 48

Acircle has a circumference of 7.850 units. what is its radius?

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.