Hi, can you please give me some hints to show that
\frac{|a-b|}{1+|a|+|b|} \leq \frac{|a-c|}{1+|a|+|c|}+\frac{|c-b|}{1+|c|+|b|}, \forall a, b, c \in \mathbb{R}.
I tried to get this from
|a-b| \leq |a-c|+|c-b|, \forall a, b, c \in \mathbb{R},
but I couldn't succeed.
Thank you.