Factory A sells 2 chickens, 4 ducks, and 5 geese for 290 yuan, and factory B sells 3 chickens, 5 ducks and 7 geese for 395 yuan. How much does it cost to sell 2 ducks and 1 goose? (This question is a student's memory, there may be deviations in the data)
甲厂卖2只鸡、4只鸭、5只鹅卖了290元，乙厂卖3只鸡5只鸭7只鹅卖了395元，问2只鸭、1只鹅卖多少元．(本题为学生回忆，数据上可能存在偏差)
<gadget id="calculator">290 * 3</gadget>
<output>870</output>

<gadget id="calculator">395 * 2</gadget>
<output>790</output>

<gadget id="calculator">870 - 790</gadget>
<output>80</output>

<result>80</result>