SOLUTION: goofy left his home by car, traveling at a rate of 30 mph. two hours later his brother pluto left his home traveling on the same road at a rate of 45 mph. in how many hours did plu

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Question 551951: goofy left his home by car, traveling at a rate of 30 mph. two hours later his brother pluto left his home traveling on the same road at a rate of 45 mph. in how many hours did pluto overtake goofy?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Goofy had a head start of
+d%5B1%5D+=+30%2A2+
+d%5B1%5D+=+60+ mi
Start a stopwatch when Pluto leaves
Let +d+ = distance that Pluto travels until they meet
Let +t+ = time on stopwatch when Pluto
overtakes Goofy
Goofy's equation:
(1) +d+-+60+=+30t+
Pluto's equation:
(2) +d+=+45t+
---------------
Substitute (2) into (1)
(1) +45t+-+60+=+30t+
(1) +15t+=+60+
(1) +t+=+4+ hrs
Pluto overtook goofy in 4 hrs
check:
(2) +d+=+45t+
(2) +d+=+45%2A4+
(2) +d+=+180+ mi
and
(1) +d+-+60+=+30t+
(1) +d+-+60+=+30%2A4+
(1) +d+=+120+%2B+60+
(1) +d+=+180+ mi
OK