How to make a fair business agreement when two guys start a company: one guys sits at home and codes for 2 months, the other pays him $50/hour to do it?

I'm thinking
1) both guys start out owning 50% of the venture
2) first guy puts in an hour of work, second guy puts in $50
3) but the first guy also gets $50 from the venture for that hour
4) this has to be repaid somehow back to the venture, at its next liquidity event

How much to repay? I see two options:
a) convertible note - if you got paid a total of $10k, you should repay $20k
b) buying back the shares - Assume that a liquidity event happens in 2 months,
with an implied valuation of val[2months].
Get an initial valuation of the venture based on opportunity cost of both people,
and make a series:
	shares = SUM {n=1 to 100} ( val[t[n+1]] / ($paid[t[n+1]] - $paid[t[n/nic]]) )
this is the percentage of total shares the borrower "sold" to the venture.
The borrower will have the option of buying them back at val[2 months] * shares.

How to repay it?
The money will come from the investor. Both founders should receive enough money
to cover the repayment of what they borrowed from the venture. From then on,
they can be paid a salary.