The juvenile sports school has three ammunition boxes of different volumes, which contain bullets for shooting practice. There are 303 rounds of bullets in the first box, the bullets in the second box account for one-fifth of the total number of bullets in the three boxes, and the bullets in the third box account for some seventh of the total number of bullets in the three boxes (several seven is the simplest score), how many bullets are there in these three boxes.
少年体校有三只容积不同的弹药箱，内装射击练习用的子弹．第一箱中装子弹303发，第二箱里的子弹占三箱子弹总数的五分之一，第三箱里的子弹占三箱子弹总数的七分之若干(七分之若干为最简分数)，这三箱里的子弹共有多少发．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (1/5) - (5/7)</gadget>
<output>3/35 = around 0.085714</output>

<gadget id="calculator">303 / (3/35)</gadget>
<output>3_535</output>

<result>3_535</result>