Question 499020: By increasing her usual speed by 25 kilometers per hour, a bus driver decreases the time on a 25-kilometer trip by 10 minutes. Find the usual speed.
The Vilas County News earns a profit of $20 per year for each of its 3,000 subscribers. Management projects that the profit per subscriber would increase by 1¢ for each additional subscriber over the current 3,000. How many total subscribers are needed to bring a total profit of $113,100?
Perform the operations and simplify. 1/x times x^2-15x all over x-14
Answer by ankor@dixie-net.com(22740)   (Show Source):
You can put this solution on YOUR website! By increasing his usual speed by 25 kilometers per hour, a bus driver decreases the time on a 25-kilometer trip by 10 minutes.
Find the usual speed.
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Let s = his usual speed
Change 10 min to 1/6 hr
write a time equation; time = dist/speed
Usual time - 10 min = faster time
 -  = 
multiply by 6s(s+25), results
6(s+25)*25 - s(s+25) = 6s*25
150(s+25) - s^2 - 25s = 150s
150s + 3850 - s^2 - 25s = 150s
Combine as a quadratic equation on the right
0 = s^2 + 25s - 3750
Factors to
(x-50)(x+75) = 0
Positive solution
x = 50 mph is his usual speed
:
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The Vilas County News earns a profit of $20 per year for each of its 3,000 subscribers.
Management projects that the profit per subscriber would increase by 1¢ for each additional subscriber over the current 3,000.
How many total subscribers are needed to bring a total profit of $113,100?
:
Find the present profit: 3000 * $20 = $60000
then: 113100 - 60000 = $53,100 increase in profits
Let n = number of subscribers over 3000 to increase profit by 1 cent for each
.01n = 53100
n = 
n = 5,310,000 additional subscribers, doesn't seem very realistic, does it!
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Perform the operations and simplify.
 * 
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(x - 14)
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* 
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(x - 14)
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Cancel the x and you are left with
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