Answer:
$577.27
Step-by-step explanation:
When offered 15% discount, buyer will then pay 100-15=85% of the original price hence the price offered by seller will be
0.85*$630=$535.5
Now this price is subjected to a tax of 7.8%, equivalent to 0.078 hence the buyer pays 1.078 of $535.5
1.078*$535.5=$577.269
Rounded off, this is equivalent to $577.27