Question 216049
two friends start walking in opposite directions one walks 5mph the other walks 4mph they are talking on radios with a 20mi radius how long can they talk
:
They can talk until they are more than 20 mi apart
:
Let t = how long they can talk
;
Write a distance equation dist = speed * time
:
5t + 4t = 20
9t = 20
t = {{{20/9}}}
t = 2{{{2/9}}} hrs or 2 hr and {{{2/9}}}*60 = 13.33 min
;
:
Check (20/9) ~ 2.22 hrs:
 4(2.22) + 5(2.22) =
8.88 + 11.10 = 19.98 ~ 20 mi