posted by chrissy .
A family drove 1080 miles to their vacation lodge. Because of increased traffic density, their average speed on the return trip was decreased by 6 miles per hour and the trip took 2.5 hours longer. Determine their average speed on the way to the lodge.
from the first:
time=1080/vavg putting that into the second..
1080=1080-6*1080/vavg + 2.5vavg-15
0=648+2.4 vavg^2 -15vavg
put it in standard form, use the quadratic formula. check my work.