university professor always goes to work by the car that picks him up at 8:00 am. One day, he walked to work at 7:15 in the morning, but the car still picked up the professor at the previous time, but he picked up the professor on the way. Therefore, the professor arrived at school 9 minutes earlier than usual, so how many times the speed of the car is the professor's walking speed?
某大学教授总是在上午8：00乘学校接他的汽车去上班．有一天，他在上午7点15分就步行去上班，而汽车仍按以前的时间去接教授，结果在途中接到教授．因此这天教授比往常提前9分钟到校，那么汽车的速度是教授步行速度的多少倍？
<gadget id="calculator">40.5 / 4.5</gadget>
<output>9</output>

<result>9</result>