SOLUTION: Dennis and Chris Reed leave simultaneously from the same point hiking in opposite​ directions, Dennis walking at 4 miles per hour and Chris at 2 mph. How long can they talk

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Question 1070250: Dennis and Chris Reed leave simultaneously from the same point hiking in opposite​ directions, Dennis walking at 4 miles per hour and Chris at 2 mph. How long can they talk on their​ walkie-talkies if the​ walkie-talkies have a 15 mile​ radius?
 ​(Round to one decimal​ place.)
Thank you!
Answer by algebrahouse.com(1659) About Me  (Show Source):
You can put this solution on YOUR website!
Distance = rate x time
d = rt

Dennis
rate = 4
time = t {left at same time}
d = 4t {distance = rate x time}

Chris
rate = 2
time = t {left at same time}
d = 2t {distance = rate x time}

Combined distances must be no more than 15 miles.

4t + 2t = 15 {added distances and set equal to 15}
6t = 15 {combined like terms}
t = 2.5 hours {divided each side by 6}

.5 hours is 30 minutes.

They can talk for 2 hours and 30 minutes,
or 2.5 hours as requested for rounding.

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