Xiaohua bought a bag of potato chips for 6.85 yuan, which was 1.42 yuan more than buying shrimp crackers, and 2.48 yuan less than the total amount of buying shrimp crackers and seaweed. How much did it cost to buy seaweed?
小华买了一袋薯片用了6.85元，比买虾条多用了1.42元，比买虾条和海苔的总钱数少2.48元．买海苔用了多少元？
<gadget id="calculator">6.85 + 2.48</gadget>
<output>9.33</output>

<gadget id="calculator">6.85 - 1.42</gadget>
<output>5.43</output>

<gadget id="calculator">9.33 - 5.43</gadget>
<output>3.9</output>

<result>3.9</result>