A, B, and C compete in a 100-meter sprint race. When A reaches the finish line, B runs 80 meters, and C is 30 meters away from the finish line. So, when B reaches the finish line, how far is C from the finish line?
甲、乙、丙三人进行100米短跑赛．甲到终点时，乙跑了80米，丙离终点30米．那么，当乙到终点时，丙离终点还有多远？
<gadget id="calculator">100 - 30</gadget>
<output>70</output>

<gadget id="calculator">70 / 80</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">1 - (7/8)</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">100 * (1/8)</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>