A tractor plows a field of 40 hectares, and it plows (2/5) in the morning. The rest plow 6 acres per hour. How many hours will it take to plow?
拖拉机耕一块40公亩的地，上午耕了它的(2/5)．余下的每小时耕6公亩．还要多少小时耕完？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/5) / 6</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">40 * (1/10)</gadget>
<output>4</output>

<result>4</result>