Xiaoliang's home is 600 meters away from the school, and he can walk 50 meters per minute. Once, he went to school from home, walked 150 meters, went home again because of something, and then went to school. How many minutes did Xiaoliang walk in total?
小亮家距学校600米，他每分钟可以走50米．有一次，他从家去学校，走了150米，因有事又回家，然后再到学校．小亮一共走了多少分钟？
<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<gadget id="calculator">600 + 300</gadget>
<output>900</output>

<gadget id="calculator">900 / 50</gadget>
<output>18</output>

<result>18</result>