# Reducing Output length by introducing new variables [duplicate]

I have outputs like "expression/(1+3*c^2) +anotherexpression/(1+3*c^2)" and so on.

Is there any way to set 1/(1+3*c^2)=A where A is a new variable so that the output reads like "A*expression+A*anotherexpression"?

Thanks

ReplaceAll[x/(1 + 3 c^2) + y/(1 + 3 c^2), 1/(1 + 3 c^2) -> z]