>>36302
>Are you a mathematician by any chance?
No, I got some help from internet people.
>I don't know about the math behind zakat so can't correct you but I'm wondering where you got those equations for zakat.
After each year 2.5% of your total wealth is taken as zakat, this means that the function that progresses this is:
change_in_wealth(year) => earning-weath(year)*(tax/100)
Since this is a rate of change we have to solve a derivative in order to get the amount of wealth at any given point, and that's what gives you the equation in the graph.