The engineering team paves a road, the ratio of paved to unpaved is 1:4, if another 300 meters is paved, half of the road will be paved, how long is this road?
工程队铺一条公路，已铺好的和未铺好的比是1：4，如果再铺300米，就刚好铺完这条公路的一半，这条公路长多少米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">300 / (3/10)</gadget>
<output>1_000</output>

<result>1_000</result>