Cars A, B, and C drive from A to B successively. B starts 5 minutes later than C, and catches up with C 45 minutes after departure; A starts 15 minutes later than B, and catches up with C 1 o'clock after departure. How long does it take for A to catch up with B?
甲、乙、丙三辆车先后从A地开往B地，乙比丙晚出发5分，出发后45分追上丙；甲比乙晚出发15分，出发后1时追上丙．甲出发后多长时间追上乙？
<gadget id="calculator">6 - 5</gadget>
<output>1</output>

<gadget id="calculator">15 / 1</gadget>
<output>15</output>

<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<result>75</result>