The two masters and apprentices rushed to make a batch of parts. The master made 15 per hour, and the apprentice made 12 per hour. The two worked together for 5 hours to complete the work. How many parts are there in this batch?
师徒二人赶做一批零件，师傅每小时做15个，徒弟每小时做12个，两人合作5小时全部完工，这批零件一共有多少个？
<gadget id="calculator">15 + 12</gadget>
<output>27</output>

<gadget id="calculator">27 * 5</gadget>
<output>135</output>

<result>135</result>