It takes 50 days for a road to be repaired by team A alone, and 75 days for team B to repair it alone. Now, team A will repair it alone for 10 days, and then the two teams will jointly repair it for 20 days. There are 10 kilometers left to be repaired. long.
一条公路由甲队单独修需50天，由乙队单独修需75天，现先由甲队单独修10天，又由两队合修20天，还剩10千米未修，求公路的长．
<gadget id="calculator">1 / 50</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">(1/50) * 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 75</gadget>
<output>1/75 = around 0.013333</output>

<gadget id="calculator">(1/50) + (1/75)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 20</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (1/5) - (2/3)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">10 / (2/15)</gadget>
<output>75</output>

<result>75</result>