Prove that $R$ is an equivalence relation where $ R:N\times N \to N $ defined as $(a,b) R (c,d)$ if and only if $ad(b+c) = bc(a+d).$

Question

Prove that $R$ is an equivalence relation where $R:N\times N \to N$ defined as $(a,b) R (c,d)$ if and only if $ad(b+c) = bc(a+d).$

I have proved for reflexive and transitive but having a problem in proving for symmetric, please help, thank you.