When processing a batch of parts, the ratio of completed parts to the total number is 1:3. If 150 more parts are processed, then (1/2) of the total number is completed. How many parts are there in this batch?
加工一批零件，已完成的与总个数的比是1：3，如果再加工150个，那么就完成了总数的(1/2)，这批零件有多少个？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(1/2) - (1/3)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">150 / (1/6)</gadget>
<output>900</output>

<result>900</result>