Shooting training regulations: shoot with a rifle, send 10 bullets, and reward 2 bullets every time you hit the bullseye; shoot with a pistol, send 14 bullets, and reward 3 bullets every time you hit the bullseye. Teacher Wang shoots with a rifle, and Teacher Li shoots with a pistol. When they finish firing all the bullets they were issued and rewarded, the number of times they shoot is equal. Mr. Wang hits the bull's-eye 20 times, how many times does Mr. Li hit the bull's-eye?
射击训练规定：用步枪射击，发10发子弹，每击中靶心一次奖励2发子弹；用手枪射击，发14发子弹，每击中靶心一次奖励3发子弹．王老师用步枪射击，李老师用手枪射击，当他们把发的和奖励的子弹都打完时，两人射击的次数相等．王老师击中靶心20次，李老师击中靶心多少次．
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">10 - 14</gadget>
<output>-4</output>

<gadget id="calculator">40 + (-4)</gadget>
<output>36</output>

<gadget id="calculator">36 / 3</gadget>
<output>12</output>

<result>12</result>