Question: Help on a Propositional Calculus question

Can someone please help me on this question ?

 

 

 

Verify this by showing how to deduce Σ

The Propositional Calculus “Extra Assumption” rule is, in fact, redundant.∪ {B} : A from Σ : A in several steps

without

[Hint: make use of

using “Extra Assumption”.-intro and -elim.]

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