Answer: 12
Work the problem in reverse:
9 - (-6) = 15
15 x 4 = 60
60/5 = 12
To make sure it’s correct, start with the number 12:
12 x 5 = 60
60/4 = 15
15 + (-6) = 9
Answer:
BC and AD mean the same thing as BCE and CE. Image via Artoba Tours.
x= 8 , -3
<h3>What is Quadratic Equation?</h3>
Given:
x² - 5x -24 =0
x² - 8x + 3x -24=0
x(x-8) + 3(x- 8)=0
(x-8)(x+3)=0
x= 8 , -3
Learn more about quadratic equation here:
brainly.com/question/1503435
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Solution
Let take boat speed = x
Current speed = 4
Upstream = x - 4
Downstream = x + 4
Distance = 9
Time upstream + Time downstream = 10
Time = Distance/Speed
9/(x + 4) + 9/(x - 4) = 10
Solving this equation 9(x-4)+9(x+4) = 10(x^2 -16)
9x - 36 + 9x + 36 = 10x^2 - 160
18x = 10x^2 -160
10x^2 -18x - 160 = 0
Now solving the above quadratic equation, we get
x = 5 or x = -16/5
We ignore the negative value.
The answer is 5.
The speed of the boat in still water is 5mph.
Thank you.