There are four baskets of bananas A, B, C, and D. The average weight of each basket of A, B, and C is 28 kg. The average weight of each basket of B, C, and D is 32 kg. The D basket contains 40 kg of bananas. How many kilograms?
有甲、乙、丙、丁四筐香蕉，甲、乙、丙三筐平均每筐重28千克，乙、丙、丁三筐平均每筐重32千克，丁筐有香蕉40千克，甲筐有多少千克？
<gadget id="calculator">28 * 3</gadget>
<output>84</output>

<gadget id="calculator">32 * 3</gadget>
<output>96</output>

<gadget id="calculator">40 - 96</gadget>
<output>-56</output>

<gadget id="calculator">84 + (-56)</gadget>
<output>28</output>

<result>28</result>