There are two types of LCD TVs, A and B, with the same inventory. Type A sells 30 units, and Type B ships 10 units. At this time, the inventory of Type B LCD TVs is three times that of Type A LCD TVs. How many sets of LCD TVs A and B are in stock?
有A、B两款库存量一样多的液晶电视，A款卖出30台，B款运进10台，这时B款液晶电视的库存量是A款液晶电视的3倍．原来A、B两款液晶电视的库存量各是多少台？
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">90 + 10</gadget>
<output>100</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<result>50</result>