Question

One car travels 20km/hr faster than another. While one of them travels 240km, the other travels 180km. Find the speed of the fast car.

Answer 1

Slow car = 60mph

Fast car = 80mph

Explanation:

Slow car = x mph

Fast car = x + 20 mph

Time = y

xy = 180

xy + 20y = 240

180 + 20y = 240

60 = 20y

y = 3

Since they traveled for 3 hours,

3x = 180

x = 60

Slow car = 60mph

Fast car = 80mph

Answer 2

80 km/h

Explanation:

speed of fast car= f

speed of the other car= s

• f= s+20
• 240/f= 180/s
• 240/(s+20)= 180/s
• 240s= 180s+180*20
• 60s= 180*20
• s=3*20
• s= 60 km/h
• f=60+20= 80 km/h