1. **State the problem:** Three girls paid 100 each, totaling 300, for a motel room. The correct charge was 250, so the clerk gave 50 to the attendant to return to the girls. The attendant gave 10 back to each girl (total 30) and kept 20. The girls effectively paid 90 each (90 \times 3 = 270), and the attendant has 20. The question is: where is the missing 10? 2. **Analyze the payments:** - Total paid by girls initially: 300 - Correct room charge: 250 - Amount to return: 50 - Attendant returns 10 to each girl: 10 \times 3 = 30 - Attendant keeps: 20 3. **Calculate the actual money flow:** - Girls paid 270 in total (90 each) - Out of this 270, 250 went to the motel, 20 went to the attendant - So, 270 = 250 + 20 4. **Identify the error in the problem statement:** The problem incorrectly adds the 20 the attendant kept to the 270 the girls paid, suggesting 270 + 20 = 290, which is wrong. 5. **Correct interpretation:** The 270 already includes the 20 kept by the attendant. The 30 returned to the girls is separate and should not be added to 270. 6. **Conclusion:** There is no missing 10. The confusion arises from mixing the amounts paid and returned incorrectly. **Final answer:** The missing 10 does not exist; the accounting is correct when properly understood.