Jayme D.

asked • 08/25/17

How do I solve

Allen and Dave leave from the same point driving in opposite directions Allen driving at 55 mph and Dave Drive at 65 mph Allen has one hour Headstart how long will they be able to talk on their car phones if the phones have a 250 mile range

2 Answers By Expert Tutors

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Arthur D. answered • 08/25/17

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Forty Year Educator: Classroom, Summer School, Substitute, Tutor
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distance=rate*time
d=r*t
250=55(t+1)+65t
250=55t+55+65t
250-55=120t
195=120t
t=195/120
t=39/24
t=13/8
t=1 5/8 hours or 1.625 hours or 1 hour 37.5 minutes they will be able to talk on their car phones
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Jayme D.

The Answer in the book says 2 hrs 37.5 minute. I got the same answer as you but my teach is saying it's wrong
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08/25/17

Arthur D.

tutor
let's check the answer...
55*(1 5/8 + 1)+65(1 5/8)
55*(2 5/8)+65(1 5/8)
55*(21/8)+65(13/8)
(55*21)/8+(65*13)/8
1155/8+845/8
2000/8=250 miles
maybe your teacher is wrong or maybe the problem has a typo or maybe the answer in the book is wrong but two tutors have the same equation
suppose the answer is 2 5/8 hours
55(3 5/8)+65(2 5/8)
55(29/8)+65(21/8)
1595/8+1365/8
2960/8=370 miles, not 250 miles so 2 5/8 cannot be correct
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08/25/17

Inactive Tutor

Jayme, on occasion (to numerous to remember/admit) I have provided an erroneous solution. 
When asking your teacher, be gentle.
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08/25/17

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