A truck drives from city A to city B at 60 kilometers per hour. After 1.5 hours, a car drives from city A to city B at 90 kilometers per hour. After a few hours, the car catches up with the truck ?
一辆卡车从A城驶向B城，每小时行60千米，开出1.5小时后，一辆轿车从A城驶向B城，每小时行90千米，几小时后，轿车追上卡车？
<gadget id="calculator">90 - 60</gadget>
<output>30</output>

<gadget id="calculator">1.5 / 30</gadget>
<output>0.05</output>

<gadget id="calculator">60 * 0.05</gadget>
<output>3</output>

<result>3</result>