Question 1166955
revenue initially is 500*80=40,000
let x change in units
so (500+25x)(80-x) needs to be maximized.
This is 40000+1500x-25x^2
the maximum value of this negative quadratic occurs when x=-b/2a, or -1500/-50 or x=30

So 1250 cups at 50 Php or 62500 Php

{{{graph(300,300,-50,40,-5000,75000,(500+25x)(80-x))}}}