Basically, what you are saying is "what would happen to the flavor if I took a can of Coke and mixed it with 2 cans of club soda?"
To get 19.2mg nic when you start out with 48, you would have 40% of the
e-liquid and 60% nicotine-free liquid (I'm rounding to make the numbers easier to deal with.)
40% e-liquid means for every 2 drops of e-liquid, you will add 3 drops of nic-free.
For everything in either of them, add up 2 of the amount in the e-liquid plus 3 of the amount in the nic-free
"amount of x in e-liquid" + "amount of x in e-liquid" + "amount of x in nic-free" + "amount of x in nic-free" + "amount of x in nic-free"
And divide the result by 5 (because you have 5 parts.)
Flavor
1 waffle + 1 waffle + 1 flavorless + 1 flavorless + 1 flavorless = 2/5 the normal amount of flavor
1 waffle + 1 waffle + 1 strawberry + 1 strawberry + 1 vanilla custard = full flavor that is 40% waffle, 40% strawberry and 20% vanilla custart
Nicotine
48 + 48 + 0 + 0 + 0 = 96/5 = 19.2
36 + 36 + 12 + 12 + 12 =108/5 = 21.6
% VG
10 + 10 + 30 + 30 + 30 = 110/5 = 22%
You don't have to be using 5 parts. You could want a mix that's 3 part 48mg and 4 parts nic-free. Then you'd have 7 total parts:
48 + 48 + 48 + 0 + 0 + 0 + 0 = 144/7 = 20.6mg