The mechanical farming team wants to plow A and B two fields. A has 6.7 hectares, plows 0.8 hectares per hour, and B has 1.7 hectares, plows 0.2 hectares per hour. The two tractors start working at the same time. After how many hours, what is left on A The land is three times that of land B.
机耕队要耕甲，乙两块地，甲地有6.7公顷，每小时耕0.8公顷，乙地有1.7公顷，每小时耕0.2公顷，两拖拉机同时开工，经过多少小时后，甲地剩下的土地是乙地的3倍．
<gadget id="calculator">3 * 1.7</gadget>
<output>5.1</output>

<gadget id="calculator">6.7 - 5.1</gadget>
<output>1.6</output>

<gadget id="calculator">3 * 0.2</gadget>
<output>0.6</output>

<gadget id="calculator">0.8 - 0.6</gadget>
<output>0.2</output>

<gadget id="calculator">1.6 / 0.2</gadget>
<output>8</output>

<result>8</result>