A bamboo pole is 4.2 meters long, 2/7 of the full length is used for the first time, and 1.3 meters is used for the second time, how many meters are left?
一根竹竿长4.2米，第一次用去全长的(2/7)，第二次用去1.3米，还剩多少米？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">4.2 * (5/7)</gadget>
<output>3</output>

<gadget id="calculator">3 - 1.3</gadget>
<output>1.7</output>

<result>1.7</result>