A 500mL of bottled water costs 10 pesos. In 100mL its cost is 2 pesos. How much is the cost of 100mL of tap water if your bill is 924 pesos in 42 cubic meter or 42,000,000 milliliters
924/4.2*10^6 * 100 = 0.0022 pesos
why mention bottled water at all?