The master and the apprentice produce a total of several parts, and the parts produced by the apprentice account for 2/5 of the total number of parts. If the apprentice gives 15 pieces to the master, the ratio of the number of parts produced by the apprentice to the master is 1:3, and the apprentice produces How many parts?
师徒两人共生产零件若干个，徒弟生产的零件占零件总数的(2/5)，若徒弟给师傅15个，则徒弟与师傅生产的零件个数的比是1：3，徒弟生产了多少个零件？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">15 / (3/20)</gadget>
<output>100</output>

<gadget id="calculator">100 * (2/5)</gadget>
<output>40</output>

<result>40</result>