rode a bicycle to the city to do errands. After leaving, B found that he had forgotten something, so he immediately chased after him on a motorcycle. B chased after 15 minutes but failed to catch up. Passed by here 20 minutes ago. B looks at his watch, it is 1 hour away from A's departure time. How many minutes does B need to catch up with A?
甲骑自行车到城里去办事，走后，乙发现他忘了一物，立即骑摩托车去追，乙追了15分钟还没追上，连忙问路旁人，路旁的人回答说：甲在20分钟前经过这里．乙看看手表，这时离甲出发时间1小时．乙需要再行几分钟就能追上甲？
<gadget id="calculator">60 - 20</gadget>
<output>40</output>

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) - (1/40)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">20 / (1/24)</gadget>
<output>480</output>

<gadget id="calculator">(1/40) * 480</gadget>
<output>12</output>

<result>12</result>