Pour out (1/3) of a bottle of juice for the first time, then pour 40ml back into the bottle; pour out the remaining juice (5/9) in the bottle for the second time, then pour out 180ml again, It was found that there were 60 ml of juice left in the bottle. How many milliliters of juice was initially in the bottle.
第一次倒出一瓶果汁的(1/3)，然后把40毫升倒回瓶中；第二次再倒出瓶中剩下果汁的(5/9)，然后又把180毫升倒去，发现瓶中还剩下60毫升果汁．问瓶中最初有多少毫升果汁．
<gadget id="calculator">60 + 180</gadget>
<output>240</output>

<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">1 - (5/9)</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">240 / (4/9)</gadget>
<output>540</output>

<gadget id="calculator">540 - 40</gadget>
<output>500</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">500 / (2/3)</gadget>
<output>750</output>

<result>750</result>