It takes 12 hours for A to make a batch of parts alone, and 15 hours for B to make it alone. A and B cooperate with this batch of parts. When they are completed, B makes 180 parts. How many parts are there in total?
一批零件，甲单独做要12小时，乙单独做要15小时，甲乙合作这批零件，完成时乙做了180个，这批零件共有多少个？
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">180 * (5/4)</gadget>
<output>225</output>

<gadget id="calculator">225 + 180</gadget>
<output>405</output>

<result>405</result>