There are three baskets of apples with an average weight of 30 kilograms each. It is known that the weight ratio of the three baskets is 9:7:2, so how much more is the weight of the heaviest than the lightest.
有三筐苹果平均每筐重30千克，已知三筐重量的比是9：7：2，那么最重的比最轻的多多少千克．
<gadget id="calculator">9 + 7 + 2</gadget>
<output>18</output>

<gadget id="calculator">9 / 18</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / 18</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/2) - (1/9)</gadget>
<output>7/18 = around 0.388889</output>

<gadget id="calculator">30 * 3 * (7/18)</gadget>
<output>35</output>

<result>35</result>