Here we have to assume that Juan does not work 24 hours. So we assume that Juan works for 'X' hours per day.
Further we do not exactly know how many days that Juan works per week. Let us assume that to be Z days. How ever `1<=Z<=7` and Z is an integer.
Then we can assume that 'Y' number of people signup for company credit card per day. Y is an integer and `Y>=0`
The daily earnings will be as follows.
Hourly payment for Juan in $`= 6`
Daily payment for working hours in $`= 6X`
Earnings by signup per day in $`= 5Y`
= (number of days worked)`xx` (daily earnings)
So the expression for weekly earnings as follows;
Weekly earnings = Z(6X+5Y)