Introduction to the fishing ground: The fishing ground is divided into four ponds: A, B, C, and D. (A and B are white crucian carp ponds, C is African crucian carp pond, and D is miscellaneous fish pond). The fishing ground charges 10 yuan/hour. To rent a fishing rod, a deposit of 100 yuan is required and a rent of 10 yuan is required. There is also a shrimp fishing farm in the fishing ground, and the shrimp fishing fee is 15 yuan/hour.