It takes 18 minutes for Xiaomei to go to grandma's house by car, but it takes 45 minutes for Xiaomei to go by car and walk back. How many minutes did he walk on his return?
小美去奶奶家，如果来去都乘车要用18分钟，小美去时乘车，回来时步行，一共用了45分钟．他回来时步行用了多少分钟？
<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">45 - 9</gadget>
<output>36</output>

<result>36</result>