math
posted by chrissy on .
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.
helppp?!?

1080=vavg*time
1080=(vavg6)(time+2.5)
from the first:
time=1080/vavg putting that into the second..
1080=(vavg6)(1080/vavg +2.5)
1080=10806*1080/vavg + 2.5vavg15
0=648+2.4 vavg^2 15vavg
put it in standard form, use the quadratic formula. check my work.
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