The ratio of the walking speeds of A and B is 8:7. A and B start from A and B respectively at the same time. If they are walking towards each other, they will meet after 0.5 hours; if they are walking in the same direction, then A will catch up with B. How many hours will it take.
甲、乙两人步行的速度之比是8：7，甲、乙分别从A、B两地同时出发，如果相向而行，0.5小时以后相遇；如果它们同向而行，那么甲追上乙需要多少小时．
<gadget id="calculator">7 + 8</gadget>
<output>15</output>

<gadget id="calculator">8 - 7</gadget>
<output>1</output>

<gadget id="calculator">0.5 / 1</gadget>
<output>0.5</output>

<gadget id="calculator">15 * 0.5</gadget>
<output>7.5</output>

<result>7.5</result>