Trouble with related rates

[Elle___1]

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Im having trouble with number 20. The answer is 480km/h, but I can’t seem to get there.

 

[stapel]

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Im having trouble with number 20. The answer is 480km/h, but I can’t seem to get there.

Neither link appears to be valid. Kindly please retry.

When you reply, please include a clear listing of your thoughts and efforts so far, so we can see what's going on.

Thank you!

 

[Steven G]

If you showed us your work and the problem, then we can help you see where you are making any mistakes. This is a help forum so no one here will solve this problem for you - since that will not be helpful.