There are 240 ping pong balls in one pocket and 60 ping pong balls in the second pocket. Take 12 ping pong balls from the first pocket and put them in the second pocket each time, and take out the ping pong balls from the second pocket at the same time. Put 7 balls into the first pocket (this counts only once). Question: How many times does this take to make the two pockets have the same number of ping pong balls?
一个口袋里有乒乓球240个，第二个口袋里有乒乓球60个，每次从第一个口袋里取出12个乒乓球放入第二个口袋里，同时从第二个口袋里取出乒乓球7个放入第一个口袋里(这样只算一次)．问：这样取多少次才能使两个口袋里的乒乓球一样多？
<gadget id="calculator">240 - 60</gadget>
<output>180</output>

<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">180 / 2 / 5</gadget>
<output>18</output>

<result>18</result>