William has a lemonade stand. It costs him $0.30 to make 3 cups of lemonade. Which of the following represents the rate of change of his cost with respect to the dozens of cups of lemonade he makes?

Rhombus adef is inscribed into a triangle abc so that they share angle a and the vertex e lies on the side bc . what is the length of the side of the rhombus if ab=c, and ac=b.

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab

The evening newspaper is delivered at a random time between 5: 30 and 6: 30 pm. dinner is at a random time between 6: 00 and 7: 00 pm. each spinner is spun 30 times and the newspaper arrived 19 times before dinner. determine the experimental probability of the newspaper arriving before dinner.