The soldiers of the People's Liberation Army carried out camping training and walked a total of 7.35 kilometers. The first 0.5 hours walked on mountain roads, with an average of 3 kilometers per hour, and then walked on flat roads, with an average of 4.5 kilometers per hour. How many hours did they travel on level roads?
解放军战士进行野营训练，共行7.35千米，前0.5小时走山路，平均每小时行3千米，后来走平路，平均每小时行4.5千米．他们在平路上行了多少小时？
<gadget id="calculator">0.5 * 3</gadget>
<output>1.5</output>

<gadget id="calculator">7.35 - 1.5</gadget>
<output>5.85</output>

<gadget id="calculator">5.85 / 4.5</gadget>
<output>1.3</output>

<result>1.3</result>