There are 5 boxes, each box contains duck eggs of equal quality. If 6 kilograms are taken out of each of the 5 boxes, the quality of the remaining duck eggs is equivalent to the duck eggs in the original 3 boxes. How many kilograms of duck eggs are in each box?
5只箱子，每只箱子装的鸭蛋质量相等．如果5只箱子里各取出6千克，剩下的鸭蛋质量相当于原来3只箱子里的鸭蛋．原来每只箱子鸭蛋多少千克？
<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">6 * (5/2)</gadget>
<output>15</output>

<result>15</result>