If 2 catties of oil can be exchanged for 5 catties of meat, 7 catties of meat can be exchanged for 12 catties of fish, and 10 catties of fish can be exchanged for 21 catties of beans, then how much oil can be exchanged for 27 catties of beans.
如果2斤油可换5斤肉，7斤肉可换12斤鱼，10斤鱼可换21斤豆，那么27斤豆可换多少油．
<gadget id="calculator">10 / 21</gadget>
<output>10/21 = around 0.47619</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

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

<gadget id="calculator">(10/21) * (7/12) * (2/5) * 27</gadget>
<output>3</output>

<result>3</result>