A storybook has 180 pages and is planned to be read in 15 days. As a result, I read 45 pages in the first 3 days. According to this calculation, how many pages are needed to finish reading the rest of the storybook? (Solve with ratio)
一本故事书180页，计划用15天读完．结果前3天读了45页，照这样计算，读完剩下的故事书还要多少页？(用比例解)
<gadget id="calculator">180 - 45</gadget>
<output>135</output>

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

<gadget id="calculator">135 / 15</gadget>
<output>9</output>

<result>9</result>