Answer:
The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable, but we can work out its value if we try! A variable doesn't have to be "x", it could be "y", "w" or any letter, name or symbol.
Step-by-step explanation:
Domain are x values (independent variable);
Speed would be independent so what speeds can be used ? -30 mph, 30 mph, 1000 mph?
Can a car go 0 mph?
What is realistic?
I would say 0 greater or equal to x greater than whatever you think is beyond the max that a car can go.
Answer:

Step-by-step explanation:
The trick here is to know the distance formula (a formula that helps you find the distance between two points).
Distance formula: distance = 
But now that we know this, we can simply plug in our values and solve!

Now we can tell from our answer that the distance between both points is 



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Answer : B
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I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey