Mr Tan recently found a new job after upgrading his skills. When he received his first-month salary, he deposited half of the salary in the bank. He used
1
3
of the remaining salary to buy a necklace for his wife, and then he bought his friends 15 dinner vouchers, worth $8 each. In the end, he had $720 left in his wallet. What was Mr Tan's first-month salary?