You are hiking on a trail that leads down from the top of a mountain. at 2 p. m. you are at an elevation of 4000 feet. at 5 p. m. you are at an elevation of 3250 feet. what is your mean hourly change in elevation?

You are -3250 below from the top of the mountain.

this is a direct variation proportion. y = kx

y is the total amount due, k is the constant of variation, and x is the number of texts sent.

plug in the 3.20 and the 16 to solve for the "k". this is the constant of proportionality. it is the value that will not change.

3.20 = k(16). solving you get $.20 per text.

the equation would then be y = .20x