Distance to Point of Equal Time (PET) =  D x H

                                                                              (O + H)

Distance to PET is directly proportional to D (total distance)

to PET is directly proportional to H (groundspeed ‘home’ (back))

Distance to PET is inversely proportional to (O + H) (sum of groundspeed ‘out’ and groundspeed ‘home’ (back))