"A grower has 100 tonnes of potatoes that she can sell now for a profit of $500 per tonne. For each week that she delays shipment, she can produce an additional 10 tonnes of potatoes. However, for each week she delays, the profit decreases $25 a tonne."

So I figured that if I could write all the information so that they are all related to the number of weeks (or as it relates to tonnes?) I could get a quadratic equation. There are questions like:

a) when should she ship to maximize her profit, and what is the maximum profit?

but if I just have the quadratic equation I can do the questions.. what I'm getting isn't working.

Help would be much appreciated! Thanks!