Calculating protocol overhead of a single HTTP response using Wireshark

I'm a newbie when it comes to networking and Wireshark so go easy on me :)

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I have an assignment for school, where we are instructed to capture HTTP requests and responses of a VM with wireshark, calculate how much (in bytes), the different protocols (ethernet, IP, TCP, HTTP) used and then calculate the protocol overhead.

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The teacher's example solution was this

Ethernet: 14 bytes

IP: 20 bytes

TCP: 32 bytes

HTTP payload: 291 bytes

Trailer: 4 bytes

Protocol overhead: (14 bytes (ethernet) + 4 bytes (trailer)) + (20 bytes (IP)) + (32 bytes (TCP)) = 70 bytes

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I can find everything else using Wireshark, except for the trailer. Where can I find this in the interface?