certain area has 520 square kilometers of land, including 20 square kilometers of desert wasteland. Due to the deforestation in this area, this area is deserted at a rate of 4 square kilometers per year. What is the percentage of the whole area.
某地区有土地520平方千米，其中沙漠荒地20平方千米，由于该地区的乱砍滥伐，该地区以每年4平方千米的速度沙漠化，如不加治理，8年后该地区沙漠化地带占整个地区的百分数是多少．
<gadget id="calculator">4 * 8</gadget>
<output>32</output>

<gadget id="calculator">20 + 32</gadget>
<output>52</output>

<gadget id="calculator">52 / 520</gadget>
<output>1/10 = around 0.1</output>

<result>1/10 = around 0.1</result>