Question 15
On Sunday afternoon, the neighbourhood girls play shop. They make paper money for buying and selling. Mai has ingredients but no pot, so she rents Ngọc’s pot. Ngọc charges Mai 1 unit for each minute. Mai starts renting at 3:10 p.m. and returns the pot at twenty-five minutes to four in the afternoon. Mai gives Ngọc three notes, each worth 10 units. How much change should Ngọc give Mai?
