Question

An engineer traveled 125 mi by car and then an additional 675 mi by plane. The rate of the plane was three times the rate of the car. The total trip took 7 h. Find the rate of the car.

Answer 1

Answer:

The speed of the car is 50 mph.

The speed of the plane is 150 mph.

 

Driving time = 185/50 = 3.7 hours

Flying time = 645/150 = 4.3 hours

Step-by-step explanation:

 

R be the speed of the car.

t is the driving time.

 

185 = R* t

 

645 = (3R)*(8-t) <---  the plane is 3 times as fast; the total time is 8 hours, so 8-t hours is spent flying

 

645 = 24R - 3rt <--- distributive

 

645 = 24R - 3(185)  <--- substitutes rt = 185

 

645 = 24R - 555

 

1200 = 24R

 

R = 50