Wanjia Supermarket originally had a batch of mineral water, sold 20% of it, and then shipped 120 boxes. At this time, the number of boxes of mineral water was more than the original (1/10). How many boxes of mineral water are there?
万佳超市原来有一批矿泉水，卖出20%后又运来120箱，这时矿泉水的箱数比原来的多(1/10)．原来有矿泉水多少箱？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/5) + (1/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">120 / (3/10)</gadget>
<output>400</output>

<result>400</result>