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

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.

**- Algebra House**