I tried doing it with CS-Engel to get $$

\frac{1}{a(1+b)}+\frac{1}{b(1+c)}+\frac{1}{c(1+a)} \geq \frac{9}{a+b+c+ a b+b c+a c}

$$

I thought that maybe proof that $$

\frac{1}{a+b+c+a b+b c+a c} \geq \frac{1}{3(1+a b c)}

$$ or $$

3+3 a b c \geq a+b+c+a b+b c+a c

$$, but I don’t know how

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