A man travels to work everyday at a speed of 40km/h using a car and 6km/h by walking. He arrives at his workshop in 25mins. One day his car broke down and he walked three times as far, thereby arriving at the workshop 17mins late. Calculate the distance from his house to the workshop

Answer 1

distance by car -- x
distance walking -- y

x/40 + y/6 = 25/60
times 120
3x + 20y = 50

on breakdown:
distance walking = 3y
distance by car = (x+y) - 3y = x - 2y

3y/6 + (x-2y)/40 = 42/60
times 120 again
60y + 3x - 6y = 84
3x + 54y = 84

subtract the two equations,
34y = 34
y = 1 km
x = 10 by subbing in the 1st equation.

so the distance is 11 km