The height of a ball in feet is modeled by f(x) = 16x^2 +72x. Where x is the time is seconds after it is hit vertex:

Axis of symmetry: x =

When a the ball at its highest

how high

how long was it in the air​

0.50 , 0.75

step-by-step explanation:

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