The formula you provided, -16t² + 80t, represents the height of a ball thrown vertically upwards, but it doesn't directly tell you how long the ball is in the air. To find that, you need to understand what the formula represents and how to use it.

Here's the breakdown:

* -16t²: This term represents the effect of gravity pulling the ball downwards. The "-16" is half the acceleration due to gravity (approximately -32 feet per second squared).

* 80t: This term represents the initial upward velocity of the ball. The "80" is the initial upward speed in feet per second.

To find the time the ball is in the air, follow these steps:

1. Set the formula equal to zero: This represents the moment the ball hits the ground (height = 0). So, we have:

-16t² + 80t = 0

2. Solve for t: This will give you the time values when the ball is at ground level. You can solve this quadratic equation by:

* Factoring: Factor out a -16t from both terms:

-16t(t - 5) = 0

This gives you two solutions: t = 0 (the initial launch) and t = 5 seconds (the time it hits the ground again).

3. The answer: The ball is in the air for 5 seconds.

In summary, the formula -16t² + 80t is a mathematical model of the ball's trajectory. It doesn't directly give the "time in air" but helps us calculate it by finding the time when the height is zero.