The teacher brought 500 yuan to buy "Story King" for the students. Each copy costs 25, and the teacher has 50 yuan left. How much is each "Story King"?
老师带了500元去给同学们买《故事大王》，每本要25，老师还剩下50元，每本《故事大王》要多少元？
<gadget id="calculator">500 - 50</gadget>
<output>450</output>

<gadget id="calculator">450 / 25</gadget>
<output>18</output>

<result>18</result>