Problema Solution
two brothers leave from the same point driving opposite directions the first brother driving at 70 miles
per hour and the second at 55 mph. The first brother has a one-hour head start. how long will they be able to talk on their car phones if the phones have a 240-mile range?
Answer provided by our tutors
let
v1 = 70 mph the speed of the first brother
v2 = 55 mph the speed of the second brother
t = the time of the second brother
t + 1 = the time of the first brother (he has 1 hour head start)
since they are traveling in opposite direction we need to find in how much time the distance between then will be 240 mi:
v1*(t + 1) + v2*t = 240 (since distance = speed*time)
70(t + 1) + 55t = 240
by solving we find:
t = 1.36 hr
t = 1 hr 21 min 36 sec
click here to see the step by step solution of the equation:
t + 1 = 1 hr 21 min 36 sec + 1 hr = 2 hr 21 min 36 sec
the brothers will be able to talk 2 hr 21 min 36 sec.