1 votes 1 votes OK so, I am pretty sure that I answer in the first image marked wrong is right. If not, why? How to do 2nd and 3rd? Mathematical Logic propositional-logic engineering-mathematics + – Vasu Srivastava asked Jul 2, 2017 Vasu Srivastava 175 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.