My advice is to not split it. Do you need a partner? can you afford to finance the haunt yourself?
Perhaps their is another aspect they can invest in like concessions or parking? If you need help get it- if you do not then do not.
If you do split it then agree on an amount each will put in and divide the profit up by the same percentage. you put in another $2000- then they each put in $2000 then you would each get 33.333% of the profit.