Question 156898
 Chuck and Dana agree to meet in Chicago for the weekend. Chuck travels 84 miles in the same time that Dana travels 78 miles. If Chuck's rate of travel is 3 mph more than Dana's, and they travel the same length of time, at what speed does Chuck travel?
:
Let s = C's traveling speed
then
(s-3) = D's speed
:
Write a time equation: Time = {{{dist/speed}}}
:
Given that:
C's time = D's time
{{{84/s}}} = {{{78/((s-3))}}}
Cross multiply
84(s-3) = 78s
;
84s - 252 = 78s
:
84s - 78s = +252
:
6s = 252
s = {{{252/6}}}
s = 42 mph is C's speed
:
:
Check solution find the times, confirm they are equal
84/42 = 2 hr
78/39 = 2 hr