There are 83 people in classes A and B, 86 people in classes B and C, and 88 people in classes C and D. How many people are in classes A and D?
甲乙两班共83人，乙丙两班共86人，丙丁两班共88人，甲丁两班共多少人？
<gadget id="calculator">88 - 86</gadget>
<output>2</output>

<gadget id="calculator">83 + 2</gadget>
<output>85</output>

<result>85</result>