# Re: Systems of Linear Functions

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Posted by Brad Paul on October 04, 2002 at 19:32:28:

In Reply to: Systems of Linear Functions posted by bkone on October 04, 2002 at 19:03:17:

: I am having a real difficult time trying to understand these problems when they are in a story problem type scenerio. Here is my problem I am really needing help with:
: A sporting goods company can produce a football for \$12. The daily fixed costs are \$720, and the company plans to sell each football for \$20.
: The question is: What is the profit or loss if 200 balls are sold in a day? and What is the profit or loss for 300 footballs? How many balls must they sell to produce a daily profit of \$200?
: Could you also give me a quick summary on how you figured it out if you respond so I can try it on the others I have? Thanks

Write the equation as you read the question. The equation I will write
is for how much money is made (or lost) in one day. I will call it P.

A sporting goods company can produce a football for \$12. ...
P=-12*n ...
I used -12 because this is a loss. n is the number of balls made.

The daily fixed costs are \$720,...
P=-12*n-720 ...
Again this is a minus because it is a loss. But this is a set loss
that dose not depend on how many balls are sold.

and the company plans to sell each football for \$20.
P=-12*n-720+20*n
This is positive because this is what is made when n selling a balls.

P=-12*n-720+20*n
You may simplify this equation if you like.

The for the first two questions just plug in for n.

The last question solve for n and plug in for P

the balls are made on demand only.

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