Among the calls received by the "people's hotline" in a certain city within a week, those related to housing problems accounted for (3/20), those related to road traffic problems accounted for (1/5), and the most calls related to environmental protection problems were housing problems. 4 times, is 3 times of road traffic problems. What percentage of the total number of calls to the hotline in a week are related to environmental protection issues?
某市"百姓热线"在一周内接到的电话中，有关住房问题的占(3/20)，有关道路交通问题的占(1/5)，有关环境保护问题的电话最多，是住房问题的4倍，是道路交通问题的3倍．有关环境保护问题的电话占一周热线电话总数的几分之几？
<gadget id="calculator">3 / 20</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) * 4</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>