Question 184688
If you sell n markers at price p, your income will be their product n x p. Use formula -125p+500=n to find a formula in terms of p only. 
I= n x p=_________
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I = (-125p + 500)*p

I = -125p^2 + 500p

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Graph:
{{{graph(400,300,-7,7,-400,500,-125x^2+500x)}}}
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Cheers,
Stan H.