Mr. Zhang went to work from City A to City B. He rode 15 kilometers per hour. When he came back, he rode a motorcycle and traveled 30 kilometers per hour. Motorcycles took 2 hours less than bicycles. Find the distance between A and B.
老张从甲城区到乙城区去办事，每小时骑15千米，回来时骑摩托车，每小时行30千米，摩托车比自行车少用2小时，求甲乙两城的距离．
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">30 - 15</gadget>
<output>15</output>

<gadget id="calculator">30 / 15</gadget>
<output>2</output>

<gadget id="calculator">30 * 2</gadget>
<output>60</output>

<result>60</result>