A motor ship departed from the first pier at a speed of 40 km / h. After 3 hours, a boat departed from the second

A motor ship departed from the first pier at a speed of 40 km / h. After 3 hours, a boat departed from the second pier towards him at a speed of 35 km / h and met the ship 4 hours after its departure. Find the distance between the marinas.

1. Let’s determine how long the first motor ship spent on the way before the second motor ship met.
3 + 4 = 7 hours.
2. Find out what path he has overcome during this time.
7 * 40 = 280 kilometers.
3. Let’s calculate which route the boat passed in 4 hours.
4 * 35 = 140 kilometers.
4. We find what is equal to the distance between the piers from which the ship and the boat left towards each other.
280 + 140 = 420 kilometers.
Answer: 420 kilometers.