Answer:
Chau would pay $1000 * 15% = $<<100015.01=150>>150 in income tax for the first $7000 of his taxable income.
For the remaining amount, Chau would pay $1000 - $7000 = $<<1000-7000=3000>>3000 in taxable income.
So Chau would pay an additional $3000 * 17% = $<<300017.01=510>>510 in income tax for this portion of his taxable income.
In total, Chau would pay $150 + $510 = $<<150+510=660>>660 in income tax for last year.