A worker needs to grind 200 kg of flour, and he grinds 60 kg in 3 hours. According to this calculation, how many hours will it take to grind the remaining flour?
一个工人要磨面粉200千克，3小时磨了60千克．照这样计算，磨完剩下的面粉还要几小时？
<gadget id="calculator">200 - 60</gadget>
<output>140</output>

<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">140 / 20</gadget>
<output>7</output>

<result>7</result>