Starting from home, Xiao Ming takes 30 minutes by subway to school, and 50 minutes by bus. One day, Xiao Ming takes the subway first and then transfers to the bus for some reason. It takes 40 minutes to reach the school, and the transfer process takes 6 minutes, so how many minutes did it take Xiao Ming to take the bus that day?
小明从家出发，乘地铁到学校需要30分钟，乘公交车到学校需要50分钟，某天小明因故先乘地铁，再换乘公交车，用了40分钟到达学校，其中换乘过程用了6分钟，那么这天小明乘坐公交车用了多少分钟．
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 40</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">(1/30) * 6</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(4/3) - (1/5) - 1</gadget>
<output>2/15 = around 0.133333</output>

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

<gadget id="calculator">(1/30) - (1/50)</gadget>
<output>1/75 = around 0.013333</output>

<gadget id="calculator">(2/15) / (1/75)</gadget>
<output>10</output>

<result>10</result>