How can I calculate the return of my investments?

Farmers pay interest and commissions on the principal received in Mexican pesos. Therefore, the 15% paid by the farmers will be reduced by the exchange commissions from the cryptocurrencies to the Mexican pesos and vice versa.  Orientative, we work with an 0.5% commission on each transaction so that profitability will be reduced by 1% between the two conversions. If the investor wants to calculate the investment in their currency of origin, the calculation is much more complex since the evolution of the Mexican peso with respect to the reference currency of the investor during the loan period would have to be taken into account for the calculation.