The store shipped 250 boxes of checkers, 147 boxes less than the number of chess pieces shipped, and the number of military chess pieces shipped was three times the total number of chess and checkers. How many boxes of military chess pieces were shipped?
商店运来250盒跳棋，比运来象棋少147盒，运来的军棋是象棋跳棋总数的3倍，运来军棋多少盒？
<gadget id="calculator">250 + 147 + 250</gadget>
<output>647</output>

<gadget id="calculator">647 * 3</gadget>
<output>1_941</output>

<result>1_941</result>