In the parent-child reading activity, Li Xin and her mother read the same novel. Li Xin plans to read 40 pages a day, which can be finished in 15 days. My mother reads 10 more pages than Li Xin every day. How many days does it take my mother to finish this novel?
在亲子阅读活动中，李欣和妈妈看同一部小说，李欣计划每天看40页，15天可以看完．妈妈每天比李欣多看10页，妈妈只用多少天就可以看完这本小说？
<gadget id="calculator">40 * 15</gadget>
<output>600</output>

<gadget id="calculator">40 + 10</gadget>
<output>50</output>

<gadget id="calculator">600 / 50</gadget>
<output>12</output>

<result>12</result>