Think of it like this

d= a*b

e = a*c for some a, b and c.

Then dd + e is equal to abab + a*c.

This can be changed to a(ab*b + c). Thus c is divisible by a.

>>3795

Poor variable name choosing here though. The c in e = ac isn't the same as our c (dd + e). I mean the equation holds it might just be a bit confusing

>>3797

I was just referring to >>3794. Explaining why the GCD(e, d) works.