During the May 1st period, Xiao Ming’s family went on a trip by car. When driving, his father added 30 liters of fuel to a park 180 kilometers away from the gas station. According to the calculation that each liter of gasoline can travel 8 kilometers, his mother asked Xiao Ming if he had to refuel when he came back. How many liters of gasoline? Please help Xiao Ming to calculate.
五一期间，小明一家开车出去旅游，开车时爸爸加了30升油，到距离加油站180千米的公园游玩，按每升汽油可行驶8千米计算，妈妈问小明，回来时还要加多少升汽油？请你帮助小明计算一下．
<gadget id="calculator">180 * 2</gadget>
<output>360</output>

<gadget id="calculator">8 * 30</gadget>
<output>240</output>

<gadget id="calculator">360 - 240</gadget>
<output>120</output>

<gadget id="calculator">120 / 8</gadget>
<output>15</output>

<result>15</result>