For a rope, (4/9) meters are used for the first time, and (2/9) meters are used for the second time, how many meters are shared between the two times.
一条绳子，第一次用去(4/9)米，第二次用去(2/9)米，两次共用去多少米．
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(4/9) + (2/9)</gadget>
<output>2/3 = around 0.666667</output>

<result>2/3 = around 0.666667</result>