The car drove from the city to the village in 4 hours. If he increased the average speed by 20 km / h

The car drove from the city to the village in 4 hours. If he increased the average speed by 20 km / h, he would hit 1 hour less travel time. Find the distance from the city to the village (in km).

1. Let:
v0 – average vehicle speed;
t0 = 4 hours – time spent on the way;
s is the distance from the city to the village.
2. Let’s compose the equation for the first condition of the problem:
v0t0 = s, substitute the value for t0:
4v0 = s. (one)
3. Let’s compose the equation for the second condition:
(v0 + 20) (t0 – 1) = s, hence:
3 (v0 + 20) = s. (2)
4. From equations (1) and (2) we obtain:
3 (v0 + 20) = 4v0;
3v0 + 60 = 4v0;
60 = 4v0 – 3v0;
v0 = 60 (km / h).
5. Find the distance between the city and the village:
s = 4v0 = 4 * 60 = 240 (km).
Answer: 240 km.