Dennis and Chris Reed leave simultaneously from the same point hiking in opposite directions, Dennis is 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?
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}
0.5 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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