Problema Solution
John walked 27 miles to the car dealer. Because his car was 9 times faster than he was, John drove home in 4 hours less than it took him to walk to the car dealer. How many hours did it take him to drive home?
Answer provided by our tutors
Distance = 27 miles
Speed of John = x
Speed of Car = 9x
Time
Time john takes = y
Time car takes = y-4
now make an equation
For both the equation distance is constant.
Distance = Speed * Time
27 miles = x* y ( equation 1) for John
27 miles = 9x(y-4) (equation 2) for Car
Solving for y from equation one
y= 27/x
Subbing y= 27 / x into equation 2
9x (27/x - 4) = 27
9x ( 27/x - 4x / x) = 27
243 - 36 x = 27
- 36 x = 27 - 243
-36 x = -216
x = 6
x = 6
y = 27/x
y = 27/6
y = 4.5 hours.
y - 4 = Car's time
4.5 - 4 = 0.5 hours
Time car takes to drive home 0.5 hours or 1/2 hour or 30 minutes.