27 miles. Because in one hour he does 3 miles so in 9 hours he does 27
<span>P(x)=-5x^2+300x+15,000 is the equation of a parabola and represents profit. Its graph opens down. Our job is to find the x-coordinate of the vertex (which is the x-coord of the maximum profit) and then the corresponding y-value.
The formula x = -b / (2a) will produce that x-coordinate:
-(300)
x = ------------ = 30
2(-5)
When x=30 units, y = profit = -5(30)^2 + 300(30) + 15000 = $19500 (answer)
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We know that there are 16 pieces left and that the ratio is 3 : 5. The ratio teels us there are 8 "parts" inside (because 3 + 5 = 8), so now we may just divide 16 by 8 to find out how much is one such "part":
16 ÷ 8 = 2
Now we can see that one "part" of the ratio is for 2 pieces. So if the ratio of black to red pieces is 3 : 5, then there are 3 * 2 = 6 red pieces and <u>5 * 2 = 10 black bieces</u>.
A. n+8<20 because she is gaining !
