Ok I can help
Ideally everything has to mix and each time you take out you put the exact amount in of distilled water. assuming exactly 12 quarts of mixed antifreeze and water.
Having the exact amount of fluid coming out means a lot. There is a big difference between 4 and 5 quarts. I wish you could be more specific. for this post, I assume exactly 5 quarts come out and 5 quarts go in of distilled water. Put drain plug back in and run engine. then take out 5 more quarts of mixed antifreeze/water. put exactly 5 quarts of distilled water back in.
First time:
Ideal is .5 * 12= 6 quarts of pure antifreeze.
after drain and fill of distilled water: 7*.5=3.5 quarts pure antifreeze. or 29% mixture
Second time:
16.9 percent antifreeze/water mixture.
or 1.183 quarts of antifreeze.
We need 6 quarts of pure antifreeze.
6-1.183=4.81 quarts of pure antifreeze.
But we took out five quarts
so add .19 quarts of distilled water to make it an exact 50 percent concentration of antifreeze to distilled water concentration.
I hope this helps. again the numbers change based on how much exact comes out. IF you get that info, I can update the math.
