Car Damage: Two Damagers

Hi a while ago someone crashed into my car and there was already damage there but he just added damage how are we supposed to know how much i owe him?

Shalom!

Thank you for your question.

If, the new damage brings the repair to a higher price bracket, then the new damager will have to pay the difference between what you would have paid anyways and the new price due to the new damage.

However, if you had no intention of repairing the original damage and only decided to repair the car because of the new damage, you must consider what you would have spent on the first damage.
 For example, suppose the original damage would have cost $500 to fix and you would not have repaired it at that price. But if the repair could have been done for $300, you would have gone ahead.
 In that case, the person who crashed into your car is responsible to pay for the full cost of repairing the combined damage minus $300.