In a pasture, 24 horses can eat the grass in 6 days, 30 horses can eat the grass in 4 days, how many horses can eat the grass in 12 days, (assuming that the daily growth of grass is fixed)
一片草场，24匹马6天可以把草吃完，30匹马4天可以把草吃完，多少匹马12天可以把草吃完，(假定草每天生长量是固定的)
<gadget id="calculator">30 * 4</gadget>
<output>120</output>

<gadget id="calculator">24 * 6</gadget>
<output>144</output>

<gadget id="calculator">144 - 120</gadget>
<output>24</output>

<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<gadget id="calculator">12 * 4</gadget>
<output>48</output>

<gadget id="calculator">120 - 48</gadget>
<output>72</output>

<gadget id="calculator">12 * 12</gadget>
<output>144</output>

<gadget id="calculator">72 + 144</gadget>
<output>216</output>

<gadget id="calculator">1 * 12</gadget>
<output>12</output>

<gadget id="calculator">216 / 12</gadget>
<output>18</output>

<result>18</result>