The price of a schoolbag is 4 yuan, which is 1 yuan less than three times the price of a pencil case. How much does a pencil case cost? (solution by equation)
一只书包售价4元，比一只铅笔盒的售价的3倍少1元．一只铅笔盒售价多少元？(用方程解)
<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">5 / 3</gadget>
<output>5/3 = around 1.666667</output>

<result>5/3 = around 1.666667</result>