It costs 5.6 yuan to buy a stationery box, which is 7 yuan less than buying 3 pens. How much is each pen? (solution by equation)
淘气买一个文具盒花了5.6元，比买3支钢笔少花7元，钢笔每支多少元？(用方程解)
<gadget id="calculator">7 + 5.6</gadget>
<output>12.6</output>

<gadget id="calculator">12.6 / 3</gadget>
<output>4.2</output>

<result>4.2</result>