There are 4 boxes of apples, each of the same weight. If 30 kilograms are taken from each box, the sum of the remaining apples in the 4 boxes is equal to the weight of the original box of apples. How many kilograms of apples are there in each box?
有4箱苹果，每箱同样重．如果从每箱里拿出30千克，那么4箱里剩下的苹果的总和等于原来一箱苹果的重．原来每箱有多少千克的苹果？
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">30 * (4/3)</gadget>
<output>40</output>

<result>40</result>