How do you get the output expression for this?

Attachment 25114
The answer is apparently

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( ¬A+ ¬D+AB¬CD)(¬B+C)

I'm not really sure how to get there esp.since that answer apparently looks like a composite function.

Hey xods.

Try and expand the output of the gate: remember to apply each operation in the order its given and surround that answer with brackets that feed into the next operation. Once you have the final expression, then expand all the brackets and simplify to check if it is equal to the other answer.