Problema Solution
Kathy and Gilbert drove a total of 661 miles in 12.6 hours. Kathy drove the first part of the trip and averaged 45 miles per hour. Gilbert drove the remainder of the trip and averaged 65 miles per hour. For what length of time did Kathy drive?
Answer provided by our tutors
as total distance is 661 miles and total time is 12.6 hours
let kathy drove for K hour and Gilbert for G hour
then
45*k+65*G=661
and
K+G=12.6
=> G=12.6-K
45K+65(12.6-K)=661
=> -20K=661-819=-158
=> K=7.9 hour
thus Kathy drove for 7.9 hour and Gilbert for 12.6-7.9=4.7 hours