There used to be some story books in the library, and I lent them to 5 classes, 26 for each class, and there were 57 left. How many story books were there? (solution by equation method)
图书室原来有一些故事书，借给5个班，每班26本，还剩57本，原来有故事书多少本？(用方程方法解答)
<gadget id="calculator">26 * 5</gadget>
<output>130</output>

<gadget id="calculator">130 + 57</gadget>
<output>187</output>

<result>187</result>