1. It takes 6.5 hours for two cars to travel from A to B at the same time. When A arrives at B, he immediately returns from the original road and meets B at 3 1.5 km at B. It is known that A car is 9 kilometers faster than B car per hour. How many kilometers is it between A and B?

2. Both Party A and Party B ride bicycles from Party A and Party B at the same time, moving in opposite directions. Party A travels every hour 1 1 km, and Party B travels every hour15km. After they met, they walked on for 9 kilometers apart. At this point, they have just been driving for 4 hours. How many kilometers is it between A and B?

3. A rectangular pool, 2 meters long, 50 decimeters wide, and 1 meter high, with a small hole 10 cm away from the pool surface, can hold several liters of water at most.

4. For a TV set, the shopping mall will add 35% to the purchase price, and then sell it at a 10% discount, and each TV set will be given a "taxi" fee to 50 yuan, so that each TV set can make a profit of 208 yuan. What is the purchase price of this TV set?