I would like to come up with an equation that compares how effectively one person pays off debt in comparison to another with a different income and with respect to different frames of time or payoff periods. Variables include the following:

- Paid-off Debt Amount with respect to Payoff Period = d
- Income Handicap with respect to Payoff Period = i
- Payoff Period = p
- Unforeseen Handicaps (Inheritance [+] or Unexpected Loss of Income [-]) = h

The Inheritance handicap would give the debt payer an unfair advantage, so it should affect the payoff factor negatively. Conversely, the Unexpected Loss of Income handicap (such as an unseen large expense) would make it harder to pay down the debt in a shorter time period, therefore, it should affect the payoff factor positively.

I would like to set this up so that it can be approached from any time frame for the payoff period, be it monthly, quarterly, semi-annually, or annually. I would also like the individual's income for said time frame to be factored in where a larger income becomes a negative handicap and a smaller income becomes a positive handicap.

I was thinking it may be easiest to come up with a factor that the debt amount can simply be multiplied or divided by. It would be a two-step equation:

Result = d*FACTOR or d/FACTOR

FACTOR = something with i, p, and h

Any help much appreciated!