Use 12 yuan per kilogram of grade A sugar, 7 yuan per kilogram of B grade sugar, and 6 yuan per kilogram of C grade sugar, and mix them into 8 yuan per kilogram of assorted sugar. If 1 kg of grade A sugar and 1 kg of grade C sugar, how many kilograms of grade B sugar should be added?
用12元1千克的甲级糖，7元1千克的乙级糖，6元1千克的丙级糖，混合成为每千克8元的什锦糖．如果甲级糖1千克，丙级糖1千克，应放乙级糖多少千克？
<gadget id="calculator">6 - 8 - 8</gadget>
<output>-10</output>

<gadget id="calculator">12 + (-10)</gadget>
<output>2</output>

<gadget id="calculator">8 - 7</gadget>
<output>1</output>

<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<result>2</result>