To repair a road, it takes 40 days for the repair team alone, and 50 days for the B team. Now Team B has repaired the full length (1/10), and the rest is jointly repaired by Team A and Team B. How many days will it take to finish it?
修一条马路，单独修甲队要40天完成，乙队要50天完成．现在乙队乙修了全长的(1/10)，剩下的由甲、乙两队合修，还要多少天修完？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 50</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">(1/40) + (1/50)</gadget>
<output>9/200 = around 0.045</output>

<gadget id="calculator">(9/10) / (9/200)</gadget>
<output>20</output>

<result>20</result>