There are 5 20 cent coins, 8 50 cent coins and 7 1 yuan coins in a carton. What is the probability of taking 1 yuan coins out of it?
一个纸箱中有2角硬币5个、5角硬币8个和1元硬币7个，要从中取出1元的硬币，可能性是多少．
<gadget id="calculator">5 + 8 + 7</gadget>
<output>20</output>

<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>