10. (10 points) A hotel has 100 standard rooms, with a room rate of 400 yuan/day, but the occupancy rate is only $50 \%$. If the room rate is reduced by 20 yuan, then 5 more rooms will be occupied. Find the appropriate room rate to maximize the hotel's room revenue.

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【Analysis】Calculate the hotel's revenue at the original room rate and the reduced rates, then compare them.
【Solution】From the problem, we get:
(1) The room rate is 400 yuan/day, and the number of occupied rooms is $100 \times 50\% = 50$, so the revenue from room fees is: $400 \times 50 = 20000$ yuan;
(2) The room rate is 380 yuan/day, and the number of occupied rooms is $50 + 5 = 55$, so the revenue from room fees is: $380 \times 55 = 20900$ yuan;
(3) The room rate is 360 yuan/day, and the number of occupied rooms is 60, so the revenue from room fees is: $360 \times 60 = 21600$ yuan;
(4) The room rate is 340 yuan/day, and the number of occupied rooms is 65, so the revenue from room fees is: $340 \times 65 = 22100$ yuan;
(5) The room rate is 320 yuan/day, and the number of occupied rooms is 70, so the revenue from room fees is: $320 \times 70 = 22400$ yuan;
(6) The room rate is 300 yuan/day, and the number of occupied rooms is 75, so the revenue from room fees is: $300 \times 75 = 22500$ yuan;
(7) The room rate is 280 yuan/day, and the number of occupied rooms is 80, so the revenue from room fees is: $280 \times 80 = 22400$ yuan;
(8) The room rate is 260 yuan/day, and the number of occupied rooms is 85, so the revenue from room fees is: $260 \times 85 = 22100$ yuan;
Answer: When the room rate is 300 yuan/day, the hotel's revenue from room fees is the highest.