Master Wang processes a batch of parts, and has completed (4/9) of this batch of parts, and there are still 50 parts that have not been completed. How many parts of this batch of parts have been completed by Master Wang?
王师傅加工一批零件，已经完成这批零件的(4/9)，还有50个没有完成，王师傅已经完成这批零件多少个？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (4/9)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">50 / (5/9)</gadget>
<output>90</output>

<gadget id="calculator">90 * (4/9)</gadget>
<output>40</output>

<result>40</result>