Mrs. vasquez purchases 12 gallons of chick-fil-a lemonade for $54 for a birthday party. what is the constant of proportionality that relates the cost in dollars, y, to the number of gallons, x? work it out as i don't understand this at all.

k = 4.5 $/gal

Explanation:

1) Two variables x and y are in direct proportion when the ratio y / x is constant, i.e. y / x = k.

2) The constant k is named constant of proportionality.

3) Hence, the constant of proportionality can be obtained by determining the quotient y / x for any pair of values.

In this case you have: y = $ 54, and x = 12 gallons of lemoneade, which leads to:

       k = y / k = $ 54 / 12 gallons = 4.5 $/gal

there is no diagram : /

step-by-step explanation: