Is it obligatory to share the trip expenses equally with a friend, and should one demand a percentage of the small profit made, or should it be left for him to cover the expenses?

The intent of the question is unclear to us due to conflicting meanings, but we will discuss two possibilities:

First: That the amount is a loan conditioned on an increase upon profit, with participation in loss by not taking the increase, but without deducting from the principal. This loan is forbidden because it involves explicit usury and contradicts the meaning of a good loan (Qard Hasan).

Second: That 10,000 Egyptian pounds are for Mudarabah (profit-sharing) and 7,000 Egyptian pounds are a loan. The Mudarabah contract is invalid due to the condition of the worker sharing in the loss. In this case, the capital and its profit belong to the capital owner, and the worker receives a fair wage ( اجر المثل). All losses are borne by the capital owner. Travel expenses are borne by the capital or the capital owner when the worker travels with the Mudarabah capital. However, since the Mudarabah is invalid, the worker is not entitled to maintenance expenses because he is considered like a hired laborer. Thus, the travel expenses are your friend's responsibility.