For a project, it takes 10 days for A to do it alone, and 15 days for B to do it alone. If two people cooperate, A’s work efficiency will decrease, and he can only complete the original (4/5), and B can only complete the original (9 /10), now it will take 8 days to complete this project, and the number of days for the two to cooperate should be as few as possible, so how many days should they cooperate for?
一项工程，甲独做需10天，乙独做需15天，如果两人合作，甲的工作效率就要降低，只能完成原来的(4/5)，乙只能完成原来的(9/10)，现在要8天完成这项工程，两人合作天数尽可能少，那么两人要合作多少天？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 8</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">7 / 50</gadget>
<output>7/50 = around 0.14</output>

<gadget id="calculator">(7/50) - (1/10)</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/5) / (1/25)</gadget>
<output>5</output>

<result>5</result>