Naughty has 45 extra-curricular books, Xiaoxiao has 50 extra-curricular books. What is the formula for finding naughty extracurricular books that are less than Xiaoxiao by a few percent?
淘气有45本课外书，笑笑有50本课外书．求淘气的课外书比笑笑少百分之几的算式是多少
<gadget id="calculator">50 - 45</gadget>
<output>5</output>

<gadget id="calculator">5 / 50</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>