One yuan equation application problem (sixth grade) SOS! It's 30 kilometers per hour from home to the railway station, 15 minutes earlier than the train's departure time. If it's 18 kilometers per hour, it's 15 minutes later than the train's departure time?

One yuan equation application problem (sixth grade) SOS! It's 30 kilometers per hour from home to the railway station, 15 minutes earlier than the train's departure time. If it's 18 kilometers per hour, it's 15 minutes later than the train's departure time?

If the distance is 30 km / h, it will be 15 minutes earlier than the departure time; if the distance is 18 km / h, it will be 15 minutes later than the departure time; if the distance is (30-18) / 2 = 66 + 18 = 24 km / h, it will arrive on time
Because it takes 10 minutes to arrive earlier, and because it takes 30 km / h 15 minutes earlier, then 24 + 6 / 3 * 2 = 24 + 4 = 28 km / h, it will arrive 10 minutes earlier than the train