Uncle Wang set off from the county seat to Wangzhuang to deliver fertilizers. When going there, the speed is 40 km/h. It takes 3 hours to arrive, and it takes 2 hours to return. How many kilometers faster is the speed when returning?
王叔叔从县城出发去王庄送化肥．去的时候速度为40千米/时，经过3小时到达，返回时用了2小时，返回时比去时的速度快了多少千米？
<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">40 * (3/2)</gadget>
<output>60</output>

<gadget id="calculator">60 - 40</gadget>
<output>20</output>

<result>20</result>