The series of 3 years studies problem, in 3 minutes, answer wrong , explain that it is wrong that you are improper for to play 10 this stock problem persons to be 9 persons!

One day, having young person to arrive millet walk , have bought a pair of shoe in the shop of children's footwear. This pair of shoe cost is 15 Yuan, marked price is 21 Yuan. Result is this young person draws out 50 Yuan to buy this pair of shoe. Millet step shop of children's footwear has no change at that time , has changed the change of 50 Yuan with that 50 Yuan to neighbor, seeking give young person 29 Yuan. However neighbor Hou come to discover that that 50 Yuan is false currency, the millet step shop of children's footwear has returned neighbor 50 Yuan under helplessness. Now, problem is: How much money has the millet step shop of children's footwear lost after all in trading this time? Each allows to send model book to answer once only! ! ! The answer that you make in 3 minutes is wrong , proves that you are improper for to play stock! ! !