Maris earns ($4,000 - $ 3,500 = ) $500 dollar more than Jose in salary, but Jose gets (4% - 2% =) 2 percentage point more in commissions.
So for Jose to make more money than Maris 2% of the sales value has to be more than 500$.
If 2% is 500$ than 100% is (500 / 2% * 100%) = 25,000$.
So when the value of sales exceeds 25,000$ Jose will make more money than Maris.