A piece of wood, the full length (1/3) is used for the first time, and 3.5 meters is used for the second time. The ratio of the rest to the full length is 1:4. How many meters is left for this piece of wood?
一根木料，第一次用去全长的(1/3)，第二次用去3.5米，剩下的与全长的比是1：4，这根木料还剩多少米？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">3.5 / (5/12)</gadget>
<output>8.4</output>

<gadget id="calculator">8.4 * (1/4)</gadget>
<output>2.1</output>

<result>2.1</result>