Teacher Zhang bought 6 pens and some homework books for a total of 125.5 yuan, 8.5 yuan for each pen, and 0.5 yuan for each homework book. How many homework books did Teacher Zhang buy? (column equations to solve problems)
张老师买了6支钢笔和一些作业本一共花了125.5元，钢笔每支8.5元，作业本每本0.5元，张老师买了多少本作业本？(列方程解决问题)
<gadget id="calculator">8.5 * 6</gadget>
<output>51</output>

<gadget id="calculator">125.5 - 51</gadget>
<output>74.5</output>

<gadget id="calculator">74.5 / 0.5</gadget>
<output>149</output>

<result>149</result>