There are two bags of rice, A and B, the original mass ratio is 7:3, 12 kg is poured from bag A to bag B, at this time, the weight of the two bags of rice is the same, how many kilograms of rice does bag B originally contain.
甲、乙两袋大米，原来的质量比是7：3，从甲袋中倒出12千克给乙袋，这时两袋大米一样重，乙袋原来有大米多少千克．
<gadget id="calculator">12 + 12</gadget>
<output>24</output>

<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">24 / 4</gadget>
<output>6</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<result>18</result>