There are 100 balls in box A and 80 balls in box B. How many balls are taken from box A and put into box B. The ratio of the number of balls in box A and box B is 7:11.
甲箱有100个球，乙箱有80个球，从甲箱取出多少个放入乙箱，甲、乙两箱球的个数之比是7：11．
<gadget id="calculator">100 + 80</gadget>
<output>180</output>

<gadget id="calculator">7 + 11</gadget>
<output>18</output>

<gadget id="calculator">7 / 18</gadget>
<output>7/18 = around 0.388889</output>

<gadget id="calculator">180 * (7/18)</gadget>
<output>70</output>

<gadget id="calculator">100 - 70</gadget>
<output>30</output>

<result>30</result>