Xiaohong and Xiaoming do the same oral math problems. Xiaohong does 60 oral math problems per minute, and Xiao Ming does 75 oral math problems per minute. When Xiao Ming finishes, Xiaohong still has 45 problems to solve. How many minutes did Xiao Ming finish?
小红和小明做同样的口算题，小红每分钟做60道口算题，小明每分钟做75道口算题，当小明做完时，小红还有45道没有做，小明做了几分钟？
<gadget id="calculator">75 - 60</gadget>
<output>15</output>

<gadget id="calculator">45 / 15</gadget>
<output>3</output>

<result>3</result>