Final answer:
Oscar's commission for last month was $1,095.
Step-by-step explanation:
To calculate Oscar's commission for last month, we first need to determine the amount of the sale that is subject to each commission rate. Since the total sale was $7,500 and the first $1,000 is subject to a 12% commission, that means Oscar's commission for the first $1,000 is $120 (12% of $1,000 = $120). The remaining balance of the sale over $1,000 is $6,500 ($7,500 - $1,000 = $6,500). Oscar's commission for this balance is 15% of $6,500, which equals $975 (15% of $6,500 = $975). To find Oscar's total commission, we add the commissions for the first $1,000 and the balance over $1,000: $120 + $975 = $1,095.