Which of the following situations form a proportional relationship?
a.5 dvds for $9 and 15 dvds for $27
b.6 cups of coffee for $8 and 9 cups of coffee for $14
c.3 purses for $60 and 5 purses for $90
d.12 cans for $3 and 30 cans for $7.50
e.2 ink cartridges for $25 and 4 ink cartridges for $75

Look at this expression. a3b3c a-3b-3c-1 which of the following is the simplest form of the expression above?

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

What is the result of adding the system of equations? 2x+y=4 3x-y=6