In an appliance repair station, 80% of the people are proficient in color TV repair business, 70% of the people are proficient in refrigerator repair business, and 10% of the apprentices are not familiar with the two businesses, so the percentage of the total number of workers who are proficient in both businesses Several? Answer: how much.
一家电维修站，有80%的人精通彩电修理业务，有70%的人精通冰箱修理业务，10%的徒工两项业务都不熟悉，那么两项业务都精通的占总人数的百分之几？答：多少．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">10 / 100</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">(7/10) - (9/10)</gadget>
<output>-1/5 = around -0.2</output>

<gadget id="calculator">(4/5) + (-1/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>