Xiao Zhang has 200 pencils, and Xiao Li has 20 pens. Each time Xiao Zhang gives Xiao Li 6 pencils, and Xiao Li returns Xiao Zhang 1 pen. After how many such exchanges, the number of pencils in Xiao Zhang's hand is 11 times the number of pens in Xiao Li's hand.
小张有200支铅笔，小李有20支钢笔．每次小张给小李6支铅笔，小李还给小张1支钢笔，经过多少次这样的交换后，小张手中铅笔的数量是小李手中钢笔数量的11倍．
<gadget id="calculator">20 * 11</gadget>
<output>220</output>

<gadget id="calculator">220 - 200</gadget>
<output>20</output>

<gadget id="calculator">11 - 6</gadget>
<output>5</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<result>4</result>