Question 10
A supermarket sells three kinds of rice bags: a 5 kg bag costs 80 thousand đồng, a 10 kg bag costs 153 thousand đồng, and a 15 kg bag costs 210 thousand đồng. Hạnh buys at least one bag of each kind. The average cost per kilogram of all the rice is 15 thousand đồng. What is the smallest possible total number of bags she buys? Explain your reasoning.
