The room rate was $25,the regular rate is $30,there would be a remaining $5 if the bellboy returned the $3 for each customer and he keep the remaining $2 it would still be $30,it is not supposed that the rate were $30,and returned the remaining $1 for each it does not mean that they had paid $9 each,but instead they had only paid $8.33 each and in $9 less $8.33 the difference is $.67 and that amount was in each customer so there were no amount to be found short...