There are 10 white balls, 3 yellow balls, and 7 red balls in a bag. If you touch any one, what is the probability of getting a red ball?
袋里装有10个白球、3个黄球、7个红球，任意摸一个，摸底到红球的可能性是多少．
<gadget id="calculator">10 + 3 + 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>