Two tractors are used to cultivate 24.5 hectares of land. Tractor A cultivates 4.5 hectares in 3 days, and tractor B cultivates 10 hectares in 5 days. If the two tractors start working at the same time, how many days will they finish plowing?
用两台拖拉机耕地24.5公顷，甲拖拉机3天耕地4.5公顷，乙拖拉机5天耕地10公顷，若两台拖拉机同时开始工作，多少天耕完？
<gadget id="calculator">4.5 / 3</gadget>
<output>1.5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">1.5 + 2</gadget>
<output>3.5</output>

<gadget id="calculator">24.5 / 3.5</gadget>
<output>7</output>

<result>7</result>