A number (5/7) is 20 less than 80, what is this number? (solution by equation)
一个数的(5/7)比80少20，这个数是多少？(用方程解)
<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">60 / (5/7)</gadget>
<output>84</output>

<result>84</result>