Language Proof and Logic 13.51<br/>Could someone help with completeing this proof?<br/><img src="https://media.cheggcdn.com/media%2F376%2F3762ddc3-f26e-4e83-a488-18f0ccea522b%2Fimage" alt="13.51 An sparse outline of a proof is shown below. It shows the main trick needed but leaves