I am somewhat familiar with the word "amortize" which means gradually depreciating the value of an asset. I could have sworn there is also a word "amartize" which has to do more with proportioning.
For example, if I want to figure out the true cost of driving a mile in my car I need to take my total maintenance and insurance costs and then divide them by total miles. I thought I could describe this as "amartizing the insurance and maintenance costs," but Googling has me convinced that amartize with an 'a' is not a real word.
Am I just making this word up? If so, what is the correct way to phrase that proportioning? Can I use "amortize" that way?