A and B planes take off from the same airport and fly in the same direction. The speed of a and B is 300km and 340km per hour respectively. After flying for four hours, a plane speeds up and overtakes B in two hours. What's the speed of a plane after speeding up? One more question Two athletes practice running on the track around the lake. A is 250 meters per minute, B is 200 meters. They start from the same place and direction at the same time. After 45 minutes, a catches up with B. how long is the track around the lake?

A and B planes take off from the same airport and fly in the same direction. The speed of a and B is 300km and 340km per hour respectively. After flying for four hours, a plane speeds up and overtakes B in two hours. What's the speed of a plane after speeding up? One more question Two athletes practice running on the track around the lake. A is 250 meters per minute, B is 200 meters. They start from the same place and direction at the same time. After 45 minutes, a catches up with B. how long is the track around the lake?

、
(340-300) × 4 △ 2 + 340 = 420 (km)
2、
（250-200）×4

It's not an equation. It can't multiply or divide
A bicycle has two wheels, a tricycle has three wheels, and the shed has eight cars and 20 wheels. How many bicycles and tricycles are there?
We need to think in detail,

If all eight cars have three wheels, they will have 24 wheels. If there are four more, they will have four two wheels, four three wheels
Another similar idea is that if there are two wheels, there are 16 wheels. If there are four less, the answer is four two wheels, four three wheels