Answer:
The speed of the boat in still water is 18 mph.
The speed of the current is 2 mph
Step-by-step explanation:
Let x represent the speed of the boat in still water.
Let y represent the speed of the current.
When the boat goes against the current, the speed is 16 mph. Assuming it traveled against the current while going upstream, its total speed would be (x - y) mph. It means that
x - y = 16 (equation 1)
Going downstream, the boat averages 20 mph. Assuming it traveled with the current, its total speed would be (x + y) mph. It means that
x + y = 20 (equation 2)
Adding both equations, it becomes
2x = 36
x = 36/2
x = 18 mph
Substituting x = 18 into equation 1, it becomes
18 - y = 16
y = 18 - 16
y = 2 mph
<em>Answer: h = 120 ft; w = 80 ft </em>
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<em>A = 9600 ft^2</em>
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<em>Step-by-step explanation: Let h and w be the dimensions of the playground. The area is given by:</em>
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<em>A = h*w (eq1)</em>
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<em>The total amount of fence used is:</em>
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<em>L = 2*h + 2*w + w (eq2) (an extra distance w beacuse of the division)</em>
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<em>Solving for w:</em>
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<em>w = L - 2/3*h = 480 - 2/3*h (eq3) Replacing this into the area eq:</em>
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<em>We derive this and equal zero to find its maximum:</em>
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<em> Solving for h:</em>
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<em>h = 120 ft. Replacing this into eq3:</em>
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<em>w = 80ft</em>
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<em>Therefore the maximum area is:</em>
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<em>A = 9600 ft^2</em>
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Answer:
y=30x+50 and y=40
Step-by-step explanation:
5 divide by 30 equals 6.12 minus 6 equals 6 so she has to make at least 6 pies.
