Xiao Zhang, Xiao Wang, and Xiao Li did 47 good deeds. The ratio of their good deeds is (1/3): (1/5): (1/4). How many of them did Xiao Zhang do?
小张、小王、小李三人做好事47件，他们做好事之比是(1/3)：(1/5)：(1/4)，其中小张做多少件？
<gadget id="calculator">20 + 12 + 15</gadget>
<output>47</output>

<gadget id="calculator">20 / 47</gadget>
<output>20/47 = around 0.425532</output>

<gadget id="calculator">47 * (20/47)</gadget>
<output>20</output>

<result>20</result>