SOLUTION: a person drives from town a to town b at the rate of 50 mph and then flies back at the rate of 160mph. if the total traveling time is 21 hours, how far is it from town a to town b

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Question 560320: a person drives from town a to town b at the rate of 50 mph and then flies back at the rate of 160mph. if the total traveling time is 21 hours, how far is it from town a to town b?
i have to use the formula d=r*t to set up an equation
my table i set up is
t * s(r) = d
slower speed 50D 50 d
faster speed (160+21) 160+21 d
total 21
can you please help me solve this?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +t+ = time to drive from a to b
+21+-+t+ = time to fly from b to a
Let +d+ = distance between a and b
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From a to b:
(1) +d+=+50t+
From b to a:
(2) +d+=+160%2A%28+21+-+t+%29+
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(2) +d+=+3360+-+160t+
Substitute (1) into (2)
(2) +50t+=+3360+-+160t+
(2) +210t+=+3360+
(2) +t+=+16+
and, since
(1) +d+=+50t+
(1) +d+=+50%2A16+
(1) +d+=+800+
It is 800 mi between the towns
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Your table could have entries
+50 mi/hr, +160+ mi/hr, t+, +21+-+t+, +d+