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?
Stream of thoughts:
6
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.

.

The final answer: 6