Bond Orders

Chemistry Level 2

Given,

Bond order of $\ce{{ { CO }_{ 3 } }^{ 2- }}$ is $\frac{ a }{ b }$ ; $a$ & $b$ are co-prime.

Bond order of $\ce{{ CO }_{ 2 }}$ is $c$ .

Bond order of $\ce{CO}$ is $d$ .

Find $a + b + c + d$ .

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