battery car goes back and forth between A and B for 3 hours. It is known that it travels 45 kilometers per hour when it goes there and 30 kilometers per hour when it returns. How many kilometers is the distance between A and B?
一辆电瓶车在甲、乙两地之间往返一次共用3小时，已知去时每小时行45千米，返回时每小时行30千米，甲、乙两地相距多少千米？
<gadget id="calculator">3 * 30</gadget>
<output>90</output>

<gadget id="calculator">45 + 30</gadget>
<output>75</output>

<gadget id="calculator">90 / 75</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">45 * (6/5)</gadget>
<output>54</output>

<result>54</result>