Tom went to the store to buy fruit. Lemons cost $2, papayas cost $1, and mangos cost $4. For every 4 fruits that customers buy, the store offers a $1 discount. Tom buys 6 lemons, 4 papayas, and 2 mangos. How much will he pay? Let's be accurate as possible.
For 6 lemons, Tom will pay 6 * 2 = $12. For 3 papayas, he will pay 3 * 1 = $3. For 2 mangos, he will pay 2 * 4 = $8. In total, the cost of the fruits before discount is 12 + 4 + 8 = $24. The total number of fruits is 6 + 4 + 2 = 12 fruits. For 12 fruits, Tom gets a discount of 12 / 4 = $3. Subtracting the discount offered by the store, Tom will pay 24 - 3 = $21.
The answer: 21.