Question

A bakery delivery truck leaves the bakery at 5:00 A.M. each morning on its 140-mile route. One
day the driver gets a late start and does not leave the baker until 5:30 A.M. To finish her route on time the driver
drives 5 miles per hour faster than usual. At what speed does she usually drive?

Answer 1

Answer: 39.62

Explanation: usual speed be x

today's speed = x+4

difference in time = 1/3 hours ( 20 min)

Usual time - today's time = 1/3

144%2Fx+-+144%2F%28x%2B4%29+=+1%2F3

multiply equation by 3x(x+4)

144%2A3%28x%2B4%29-144%2A3%2Ax=+x%28x%2B4%29

432x+1728-432x=x^2+4x

x^2+4x-1728=0

solve this you will get the usual speed which is

Step-by-step explanation: