2 yuan per box, buy four boxes and get one free, how much is it actually per box?
每盒2元，买四盒送一盒，实际每盒多少元？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2 * (4/5)</gadget>
<output>8/5 = around 1.6</output>

<result>8/5 = around 1.6</result>