Solve the equation: (1/3): (1/20) = 4: x3: 5 = (x+6): 20.
解方程：(1/3)：(1/20)=4：x3：5=(x+6)：20．
<gadget id="calculator">3 * 20</gadget>
<output>60</output>

<gadget id="calculator">60 / 5</gadget>
<output>12</output>

<gadget id="calculator">12 - 6</gadget>
<output>6</output>

<result>6</result>