Solve the equation: x+(1/4)x=20.
解方程：x+(1/4)x=20．
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">20 / (5/4)</gadget>
<output>16</output>

<result>16</result>