SOLUTION: Mary and Janet are running in the Apple hill fun run. Mary runs at 7 mph, Janet at 5mph. If they start at the same time, how long will it be before they are 1.5 miles apart .

Algebra ->  Inequalities -> SOLUTION: Mary and Janet are running in the Apple hill fun run. Mary runs at 7 mph, Janet at 5mph. If they start at the same time, how long will it be before they are 1.5 miles apart .      Log On


   

Question 995512: Mary and Janet are running in the Apple hill fun run. Mary runs at 7 mph, Janet at 5mph. If they start at the same time, how long will it be before they are 1.5 miles apart .
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = the distance in miles
Mary travels in time +t+ in hrs
+d+-+1.5+ = the distance in miles
Janet travels in time +t+ in hrs
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Mary's equation:
(1) +d+=+7t+
Janet's equation:
(2) +d+-+1.5+=+5t+
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Substitute (1) into (2)
(2) +7t+-+1.5+=+5t+
(2) +2t+=+1.5+
(2) +t+=+.75+
and
+.75%2A60+=+45+
In 45 min they will be 1.5 mi apart
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check:
(1) +d+=+7t+
(1) +d+=+7%2A.75+
(1) +d+=+5.25+
and
(2) +d+-+1.5+=+5t+
(2) +d+-+1.5+=+5%2A.75+
(2) +d+-+1.5+=+3.75+
(2) +d+=+5.25+
OK