The curly hair processed by the wig factory this month is 3 times that of straight hair, and 15,000 sets of curly hair are more than straight hair. How many sets of straight hair are there?
假发厂本月加工的卷发是直发的3倍，卷发比直发多15000套．直发有多少套．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">1_500 / 2</gadget>
<output>750</output>

<result>750</result>