During normal breathing, about 11% of the air in the lungs is replaced with each breath. Write an exponential decay model for the amount of original air left in the lungs if the initial amount of air in the lungs is 550 milliliters. How much of the original air is present after 30 breaths? Complete the equation with the known values, and then find the amount of air left after 30 breaths. A = x The amount of air left after 30 breaths is. milliliters.