You have made aprox 9.5% solution.
The maths is below.
If your going to mix solutions and know what % you getting then you need to stick the the equasion:
% + % = ?? ........ ?? / 2 = new %
ALWAYS mix in equal qualtities - even if you had mixed 10ml + 10ml to get 20ml then mixed the 20ml you made with another 20ml to get 40ml and so on then you could have worked out what % you had created but because you didn't stick to equal quantities it makes the maths extreemly longwinded to do.
I worked it out that you would have mixed 10ml + 10 ml (16 + 8 = 24 .. 24 / 2 = 12%) that would have given you 20ml of 12% which you would have them mixed with 20ml of 8% which would have been (12 + 8 = 20 .. 20 / 2 = 10%) so you would have had 40ml of 10% then you added another 20ml of 8% - so you would have to had to use 20ml of the 10% you have made at this stage and add that to the 20ml of 8% leaving you with 20ml of 10% to add in again later, so (10 + 8 = 18 .. 18 / 2 = 9%) then you have 40ml of 9% and 20ml of 10% that still need adding together.
So 10ml + 10ml (9 + 10 = 19 .. 19 / 2 = 9.5%) so now you have...
20ml of 9.5%
10ml of 10%
30ml of 9%
You would then add the 10ml + 20ml together to get 30ml (9.5 + 10 = 19.5 .. 19.5 / 2 = 9.75%) then add that 30ml to the other 30ml and you would have 60ml of ......
9.75 + 9 = 18.75 .. 18.75 / 2 = 9.375%
So you had 60ml of 9.375% solution.
**Off for a nice cuppa and a choccy biccie now as that taxed my brain a bit lol**