SOLUTION: ashley's parents drives in one car at a steady rate of 40 miles per hour. Brittany's family leave 2 hours later and drives at a constant rate of 50 miles per hour. Both families ar

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Question 915598: ashley's parents drives in one car at a steady rate of 40 miles per hour. Brittany's family leave 2 hours later and drives at a constant rate of 50 miles per hour. Both families arrive at the grandparents' house at the same time! what is the distance from ashley's house to the grandparents' house?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Ashley's parents got a head start of +40%2A2+=+80+ mi
Start a stopwatch when Brittany's family leaves.
Let +d+ = the distance in miles from Ashley's house
to grandparent's house
Let +t+ = time in hrs on the stopwatch
---------------------------------
Equation for Ashley's parents:
(1) +d+-+80+=+40t+
equation for Brittany's family:
(2) +d+=+50t+
----------------
Substitute (2) into (1)
(1) +50t+-+80+=+40t+
(1) +10t+=+80+
(1) +t+=+8+
--------------
(2) +d+=+50%2A8+
(2) +d+=+400+
The distance from ashley's house
to the grandparents' house is 400 mi
--------------------
Check:
(1) +400+-+80+=+40t+
(1) +320+=+40t+
(1) +t+=+8+
OK