After repairing the full length (4/7) of a section of road, there are still 900 meters left. What is the correct formula for finding the total length of this section of road in meters?
一段公路修了全长的(4/7)后还剩下900米，求这段公路全长有多少米的正确列式是多少
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">900 / (3/7)</gadget>
<output>2_100</output>

<result>2_100</result>