Budget allocation: Find out how much can be spent based on other columns

I am unsure how to get this formula. I have my budget and i am making the allocation sheet figure out how much I am spending on what for that paycheck. The allocation sheet has 3 paychecks in it. At each paycheck I am putting additional money to debt. What I am stuck on is I want the it automatically figure out how much I can pay per paycheck so that there is enough money left for the 2nd and 3rd paycheck. Then doing same for the 2nd paycheck. If i can not put any money i want it to be 0, if I can put some but not all i want that number to return.

So i was comparing the income of all then minus expenses but it seems to be more complicated. I hope someone can help.