Question: Hawkeye is driving to his aunt. He has to charge his battery for $3.5 per charge. If he charged his battery four times, and his battery charging budget was $20, how much money was he left with when he reached his aunt's place? Think carefully first, then make a decision:
If each battery charge costs $3.5, the total expense of 4 battery charges is 4 * 3.5 = $14. After his expense on battery charging, his balance was 20 - 14 = $6. So the answer is 6.