Help with Functions (I hope this is the right section!)

EDIT: DUMB. I just saw the "Pre-Algebra and Algebra" section included functions. Sorry!

Hi! I'm a grade 11 student preparing for my winter exams, and I've come across two questions that I can't seem to solve. Any help would be greatly appreciated.

**1) A small company produces and sells x widgets per week. They find that their cost function in dollars is C(x)=$50+3x and their revenue function in dollars is R(x)=6x-(x^2/100). How many widgets per week should be produced for maximum profits?**

I attempted to do 6x-(x^2/100)=$50+3x, then got (x^2/100)+3x-50=0 and used the quadratic equation. I got the wrong answer, so I'm assuming I made a no-no in making the two functions equal each other. What are you supposed to do, if you don't mind explaining?

The second one is more confusing.

**2)A rectangular field is to be enclosed by a fence. Two fences, parallel to one side of the field, divide the field into three rectangular fields. If 2400 m of fence are available, find the dimensions giving the maximum area.**

I don't really understand how to get the answer here. Am I supposed to find the dimensions for the maximum area of the field?

Thank you!