Final answer:
According to the 20-10 rule, a person earning $1,500 a month shouldn't have monthly credit payments exceeding $300, which is 20% of their monthly income.
Step-by-step explanation:
Using the 20-10 rule, a person earning $1,500 a month shouldn't have monthly credit payments that exceed 20% of their monthly net income.
To calculate this, we take 20% of $1,500, which is $300. Therefore, the correct answer is $300.