An indirect or inverse proportion will give you a constant for the product of the two variables; lets say they are p and v. Thus:
p1v1 = p2v2 = p3v3 etc
Set up as ratio and proportions an inverse proportion will look like this
p1/p2 = v2 / v1 This way the cross product factors have the same subscripts. Notice that v1 does not appear in the corresponding numerator spot on the right side, but rather down below.
Pressure and volume vary this way, so do mass and acceleration.
