Sry for my bad english, i mean that we can calculate from 2 different points. It's either 100/67*number of turns or (67/100)/number of turns. Second term refers to a division.
Edit : I found a post related to different speed. It's pretty old but infos are correct.
from this post :
http://forums.civfanatics.com/showpost.php?p=9667635&postcount=1
Conditions are more different than I previously indicated to get any kind of streamlined result from interpreting a quick game result as a standard game.
Hammer cost of a monument
Quick: 26 \ Standard: 40 \ Epic: 60 \ Marathon: 120
Gold cost of a monument
Quick: 200 \ Standard: 280 \ Epic: 380 \ Marathon: 640
This suggests percentage scaling is 65\100\150\300 for hammers and 71\100\135\228 for gold. Or if taking quick as the baseline as it seems that you are inclined to do, 100\154\230\461 hammers and 100\140\190\320 gold.
These are inconsistent with each other as it is, and then there's science, which scales similarly to hammers but also is adjusted by a factor of map size.
I'll no longer debate this point, now knowing that there are composite variable factors that transcends the goal of juxtaposed assessment beyond multiplication, division and percentages. "I am sorry this has caused a divide between us," and I bid you good luck with grasping fundamental mathematics.