There are IQ and EQ candies in Bucktooth Rabbit's store. IQ sugar is 10 yuan per kilogram, and EQ sugar is 14 yuan per kilogram; it mixes the two kinds of sugar into QQ sugar of 13 yuan per kilogram, how many kilograms of IQ sugar and 12 kg of EQ sugar need to be mixed.
龅牙兔的商店里有IQ、EQ两种糖．IQ糖每千克10元，EQ糖每千克14元；它将两种糖混合成每千克13元的QQ糖，需要用多少千克IQ糖和12千克EQ糖混合．
<gadget id="calculator">14 * 12</gadget>
<output>168</output>

<gadget id="calculator">13 * 12</gadget>
<output>156</output>

<gadget id="calculator">168 - 156</gadget>
<output>12</output>

<gadget id="calculator">13 - 10</gadget>
<output>3</output>

<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<result>4</result>