A stone grinding machine can grind (15/7) tons of stones in (3/4) hours. According to this calculation, how many hours does it take to grind 1 ton of stones.
一台碾石机(3/4)小时可以碾石(15/7)吨，照这样计算，碾1吨石需要多少小时．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">15 / 7</gadget>
<output>15/7 = around 2.142857</output>

<gadget id="calculator">(3/4) / (15/7)</gadget>
<output>7/20 = around 0.35</output>

<result>7/20 = around 0.35</result>