Wu Yun put 143 ping-pong balls into two kinds of boxes, 12 in each big box and 5 in each small box, which was just finished. So how many more big boxes are there than small boxes?
吴韵同学把143只乒乓球放进两种盒子中，每个大盒子装12个，每个小盒子装5个，恰好装完．那么大盒子比小盒子多多少个．
<gadget id="calculator">9 - 7</gadget>
<output>2</output>

<result>2</result>