For a section of railway, the ratio of the repaired length to the unrepaired length is 4:5. If another 50 kilometers are repaired, the repaired length will account for 2/3 of the total length. How many kilometers is the total length of this railway?
一段铁路，已修的长度与未修的长度的比是4：5，如果再修50千米，已修的长度就占全长的(2/3)，这段铁路全长多少千米？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(2/3) - (4/9)</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">50 / (2/9)</gadget>
<output>225</output>

<result>225</result>