Question 509618
d = r*t is the fundamental distance equation.
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you need to know 2 of these to calculate the 3rd.
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3 mph = r
2 mph = r
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but unless you know 'd', you cannot calculate 't'
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Say d = 9
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9 = 3t
t = 9/3 = 3 hr  :  It takes 3 hr at 3 mph to go 9 miles
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9 = 2t
t = 9/2 = 4 1/2 : It takes 4 1/2 hr at 2 mph to go 9 miles.
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And so forth.