A passenger car and a truck depart from A and B respectively at the same time and travel towards each other. The speed ratio of the passenger car and the truck is 9:7. When the two cars meet, they are 20 km away from the midpoint. How many kilometers will the truck travel at this time?
客车与货车分别从A、B两地同时出发，相向而行．客车与货车的速度比是9：7，两车相遇时离中点20km，这时货车行多少千米？
<gadget id="calculator">9 + 7</gadget>
<output>16</output>

<gadget id="calculator">9 / 16</gadget>
<output>9/16 = around 0.5625</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(9/16) - (1/2)</gadget>
<output>1/16 = around 0.0625</output>

<gadget id="calculator">20 / (1/16)</gadget>
<output>320</output>

<gadget id="calculator">7 / 16</gadget>
<output>7/16 = around 0.4375</output>

<gadget id="calculator">320 * (7/16)</gadget>
<output>140</output>

<result>140</result>