Red plum water cloud cave lottery.

Solution: According to Dongfeng Travel Agency, 200 people are organized to travel to Guo Hua and Yunshui Cave, and the equation is X+Y = 200;

According to the fact that the number of people going to Huaguoshan is twice as small as that going to Yunshui Cave 1, the equation is x = 2y- 1.

Then the equation can be listed as: {x+y = 200x = 2y- 1.