PT71.S3.Q24 - If concrete is poured while

GETREQTLSAT

Okay so for this question I got it right but would have taken way less time if I understood something. I've been doing logic for a while but this one got me a little tripped.

If

A--> (C or D)

we can contra to /C--> (/A or D)??

I thought we could have to do it as such

A-->/C-->D

/A or /C-->D

/C or /A-->D

C-->/A --> D

C--> (A or D).

Where am I going wrong?

Admin note: edited title; please use the format of "PT#.S#.Q# - [brief description]"

Admin note: https://7sage.com/lsat_explanations/lsat-71-section-3-question-24/

Pride Only Hurts

Contra would be /C and /D -> /A

A and /C -> D is correct but it’s not the contrapositive.

You can’t do /A or /C -> D because once you negate the sufficient condition your rule falls away.

GETREQTLSAT

Thanks so much!