Respuesta :
Warren
drove from Townsville à Villaville at 70 miles per hour
and from Villaville to Townsville è 50 miles per hours
He drove for a total of 12 hours.
=> 70 miles + 50 miles = 120 miles
=> 12 hours
So the unit rate of his driving is 120 miles / 12 hours
=> 120 miles / 12 hours
=> 10 miles / hour
thus, he drove in total for 10 miles per hour.
And probably the 2 towns are about 60 miles away.
and from Villaville to Townsville è 50 miles per hours
He drove for a total of 12 hours.
=> 70 miles + 50 miles = 120 miles
=> 12 hours
So the unit rate of his driving is 120 miles / 12 hours
=> 120 miles / 12 hours
=> 10 miles / hour
thus, he drove in total for 10 miles per hour.
And probably the 2 towns are about 60 miles away.
Call the distance between the towns 'D' .
The time it takes to cover a distance is (distance) divided by (speed).
It takes Mr. Warren D/70 hours on the first trip,
and it takes him D/50 hours on the return.
All together, it takes him 12 hours.
D/70 + D/50 = 12 hours
Change the fractions to
a common denominator
(350) for adding: 5D / 350 + 7D / 350 = 12
Add: 12D / 350 = 12
Divide each side by 12 : D / 350 = 1
Multiply each side by 350 : D = 350 miles .
Check:
Going: 350mi / 70 mph = 5 hours
Coming: 350mi / 50 mph = 7 hours
Total 12 hours yay !