A primary school prepared a total of 180 prizes for the Children's Day Fun Fair, and spent a total of 450 yuan. Later, some prizes were added and it cost an extra 150 yuan. How many prizes did they prepare in total?
某小学为六一儿童节的游艺会准备奖品共180份，共花了450元．后来又添了一些奖品多花了150元，他们一共准备了多少份奖品？
<gadget id="calculator">450 / 180</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">150 / (5/2)</gadget>
<output>60</output>

<gadget id="calculator">60 + 180</gadget>
<output>240</output>

<result>240</result>