The installation of campus network lines in Sunshine Elementary School saved 51,000 yuan compared to the budgeted investment, which was exactly 20%. How much was the actual investment?
阳光小学安装校园网络线路，比预算的投资节约了5.1万元，正好节约了20%，实际投资多少万元？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5.1 / (1/5)</gadget>
<output>25.5</output>

<gadget id="calculator">25.5 - 5.1</gadget>
<output>20.4</output>

<result>20.4</result>