Dara drove from home to the airport to pick up her friend and then came back home on the same route.
Her average speed on the way to the airport was
55 miles
per
hour (mph), and her average speed on
the way back home was 45 mph. If the total driving
time was 1 hour and 20 minutes, how far, in miles, is
the airport from Dara's home?

33 miles

Step-by-step explanation:

Trip to airport:

distance = d1

speed = s1 = 55 mph

time = t1

Trip home:

distance = d2

speed = s2 = 45 mph

time = t2

We are told the same route was used for both trips, so

d1 = d2

The total time was 1 hr 20 min = 1 hr + 20/60 hr = 4/3 hr.

t1 + t2 = 4/3

t2 = 4/3 - t1

speed = distance/time

distance = speed * time

d1 = s1 * t1

d2 = s2 * t2

d1 = d2, so

s1 * t1 = s2 * t2

t2 = 4/3 - t1; s1 = 55; s2 = 45

55 * t1 = 45(4/3 - t1)

55t1 = 60 - 45t1

100t1 = 60

t1 = 0.6

The time to get the the airport was 0.6 hr. Now we find the distance.

d1 = s1 * t1

d1 = 55 * 0.6

d1 = 33

The distance is 33 miles.

christopher is 272,195 year old

step-by-step explanation: