For two planets orbiting the sun, do you see why it makes sense to speak of the planets as revolving around each other?

I offer this question as an introduction to a useful discovery that I made that has scant reference in the literature. I will show how it makes it easy to calculate the number of times the Earth revolves around the sun in a year and to determine how long it takes for the moon to revolve around the Earth.

If this question appears nonsensical, consider the following. Suppose the planet in the inner orbit was stationary. Then it would certainly make sense to speak of the other planet as revolving around it. Now introduce some motion to the inner planet. Shouldn’t we still be able to speak of the planets as revolving around each other? How would you define the amount by which this revolution occurs?