DAG Representation

Question

How to solve Questions of DAG like :- https://gateoverflow.in/2068/gate2014-3-34

My Solution:- (Please Point out what i am doing wrong)

and please also do tell the proper way to do such question

Comments

a=b+c and d=b+c but in between c is changing right? therefore a=d is false...

next e=d-b but d=b+c ====> e=c

next a=e+b by e=c ==> a=b+c but already b+c=d ===>a=d

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Oh yeah thats a silly mistake Thank You :)