There is a piece of wood, cut off (2/5) meters for the first time, cut off (7/10) meters for the second time, and leave (4/15) meters, how long is this wood?
有一根木头，第一次截去(2/5)米，第二次截去(7/10)米，剩下(4/15)米，这根木头有多长？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">(2/5) + (7/10) + (4/15)</gadget>
<output>41/30 = around 1.366667</output>

<result>41/30 = around 1.366667</result>