Xiaohua bought 3 packs of potato chips and 2 boxes of jelly in the supermarket, and spent a total of 12.9 yuan. It is known that each box of jelly is 1.2 yuan, how much is each bag of potato chips?
小华在超市买了3包薯片和2盒果冻，一共花了12.9元．已知每盒果冻1.2元，每包薯片多少元？
<gadget id="calculator">1.2 * 2</gadget>
<output>2.4</output>

<gadget id="calculator">12.9 - 2.4</gadget>
<output>10.5</output>

<gadget id="calculator">10.5 / 3</gadget>
<output>3.5</output>

<result>3.5</result>