SOLUTION: Kristi's ride to school is 3 minutes more than 1/2 Brianne's travel time. what graph shows the possible times of Kristi's and Brianne's rides to school?

Algebra ->  Linear-equations -> SOLUTION: Kristi's ride to school is 3 minutes more than 1/2 Brianne's travel time. what graph shows the possible times of Kristi's and Brianne's rides to school?      Log On


   

Question 824744: Kristi's ride to school is 3 minutes more than 1/2 Brianne's travel time. what graph shows the possible times of Kristi's and Brianne's rides to school?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
They travel the same distance, so
let +d+ = the distance for both
Let +t+ = Brianne's time in minutes
Let
Brianne's equation:
+d+=+r%5B2%5D%2At+
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By substitution:
+r%5B1%5D%2A%28+t%2F2+%2B+3+%29+=+r%5B2%5D%2At+
+r%5B1%5D%2Fr%5B2%5D+=+t+%2F+%28%28+t%2F2+%2B+3+%29%29+
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+r%5B1%5D%2Fr%5B2%5D+ compare the slopes of their equations
Suppose +t+=+18+ min
+r%5B1%5D%2Fr%5B2%5D+=+18+%2F+%28+18%2F2+%2B+3+%29+
+r%5B1%5D%2Fr%5B2%5D+=+18%2F12+
This says if Kristi's rate of travel is 18,
then Brianne's must be 12
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Brianne's rate will always be less than Kristi's
unless Kristi's rate is 2, then Brianne's rate is 4
or Kristi's rate is 3, then Brianne's rate is 4.5
or Kristi's rate is 4, then Brianne's rate is 5
or Kristi's rate is 5, the Brianne's rate is 5.5
If Kristi's rate is 6, then Brianne's rate is 6 also
From that rate on. Brianne's will always be less