It takes Xiao Ming 30 minutes to walk from home to school, and 12 minutes to ride a bicycle. When he started from home by bicycle for 8 minutes, the bicycle broke down and he changed to walk. How many minutes did it take Xiao Ming to go from home to school?
小明从家到学校，步行需要30分钟，骑自行车需要12分钟．当他骑自行车从家出发8分钟后，自行车坏了，改为步行．小明从家到学校共用了多少分钟？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) * 8</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/3) / (1/30)</gadget>
<output>10</output>

<gadget id="calculator">10 + 8</gadget>
<output>18</output>

<result>18</result>