A canteen buys a batch of rice, eats all (1/4) in the first week, eats the rest (2/5) in the second week, and eats (after eating in the first two weeks) and the rest (1/5) in the third week /2), if the remaining 180 catties are eaten in the fourth week, how many catties are there in total in this batch of rice?
某食堂购买一批大米，第一周吃了全部的(1/4)，第二周吃了余下的(2/5)，第三周吃了(前两周吃后)又余下的(1/2)，第四周将剩下的180斤全部吃完，则这批大米共有多少斤．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">180 / (1/2) / (3/5) / (3/4)</gadget>
<output>800</output>

<result>800</result>