Master Wang processes a batch of parts, and the ratio of the number of completed parts to the total number of parts on the first day is 1:5. If 45 more parts are processed, half of this batch of parts can be completed. How many parts will be processed by Master Wang on the first day?
王师傅加工一批零件，第一天完成的个数与零件总数的比是1：5．如果再加工45个，就可以完成这批零件的一半，王师傅第一天加工零件多少个？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">45 / (3/10)</gadget>
<output>150</output>

<gadget id="calculator">150 * (1/5)</gadget>
<output>30</output>

<result>30</result>