There are three piles of chess pieces, the second pile is 4 times more than the first pile, and the third pile is 1 less than the first pile. When the number of chess pieces in the first pile is the same, the number of chess pieces in the second and third piles is the same.
有三堆棋子，第二堆比第一堆的3倍多4个，第三堆比第一堆的4倍少1个．当第一堆棋子是多少个时，第二、三堆的棋子数相同．
<gadget id="calculator">1 + 4 + 0</gadget>
<output>5</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">5 / 1</gadget>
<output>5</output>

<result>5</result>