Each notebook is 4.5 yuan, and each pen is 7.5 yuan. Aunt Wang bought 10 notebooks and 15 pens and gave the salesperson 200 yuan. How much should I get back?
每个笔记本4.5元，每枝钢笔7.5元，王阿姨买了10个笔记本和15枝钢笔，给售货员200元，应找回多少元？
<gadget id="calculator">4.5 * 10</gadget>
<output>45</output>

<gadget id="calculator">7.5 * 15</gadget>
<output>112.5</output>

<gadget id="calculator">200 - 45 - 112.5</gadget>
<output>42.5</output>

<result>42.5</result>