What is the answer show work -15 + n = -27

How can we find the measure of an exterior angle if we know the measurement of an interior angle

The marriott family bought a new apartment three years ago for $65,000. the apartment is now worth $86,515. assuming a steady rate of growth, what was the yearly rate of appreciation? what is the percent of the yearly rate of appreciation?

Average acceleration: i have no idea how to do this.