Finding the last value that has a variation of n%

[mattkatt]

This is tough to even state, but I'll try with an example

Example: find the first value that changed 50% in relation to the last time when there was a change of 50%, beggining when the value is not zero.

A B C D E F G H

0 0 10 12 15 17 22.5 19

The first time the value changed 50% is in E, but then it changed again in G, so I need a formula that returns 22.5; if there was no 22.5, the correct answer would be 15