1. **State the problem:** Three girls paid $100 each, total $300, for a motel room. Later, the clerk realizes the room only costs $250 and gives $50 to the attendant to return. The attendant gives $10 back to each girl (total $30) and keeps $20. The question is: where is the missing $10 when the girls paid $90 each (total $270) plus $20 kept by the attendant? 2. **Clarify the situation:** Total amount paid by girls initially: $300. Correct amount for room: $250. Amount to be refunded: $50. Each girl gets $10 back, so refunds total $30. The attendant keeps $20. 3. **Calculate the actual money flow:** Money paid by girls after refund: $300 - $30 = $270. Of this $270, $250 is with the motel (actual room cost) and $20 with the attendant. So, $270 = $250 + $20. 4. **Identify the confusion:** The mistake is adding the $20 with $270. The $270 already includes the $20 kept by the attendant. It is incorrect to do $270 + 20 = $290 and look for $10 difference. 5. **Correct interpretation:** Girls paid $270 total. $250 is room cost. $20 is with the attendant. Sum of these is $270, matching the amount each girls effectively paid. No money is missing. **Final explanation:** The "missing" $10 is a result of an incorrect sum. The $20 held by attendant is part of the $270 the girls paid, not additional. The problem is a classic misdirection. **Answer:** No money is missing. The $270 the girls paid includes the $20 kept by the attendant and $250 paid for the room.