A, B, and C start from point A at the same time, drive to point B along the same route, and catch up with the same cyclist who is going from point A to point B at 12 minutes, 15 minutes, and 20 minutes respectively. Everyone moves forward at a constant speed, A's speed is 35 kilometers per hour, B's speed is 30 kilometers per hour, find C's speed.
甲、乙、丙三人同时从A地出发，沿同一路线驱车前往B地，分别在12分钟、15分钟、20分钟时追上同一个正从A地前往B地的骑车人，若所有人均为匀速前进，甲的速度为每小时35千米，乙的速度为每小时30千米，求丙的速度．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">35 - 30</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) - (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/5) / (1/20)</gadget>
<output>4</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">30 - 20</gadget>
<output>10</output>

<gadget id="calculator">15 + 10</gadget>
<output>25</output>

<result>25</result>