Dilute chemicals?

So ive got to make a 1 liter 10% mix of Ammonia out of a 25% mix i currently have.
Will it be just as easy as adding 400ml of 25% Ammonia to 600ml of water to achieve my final 10% mix ratio?
Do i have to take molecular mass into consideration?
Thanks
PS i'm not a terrorist

Thanks mate just double checking

Thank christ.
I thought i had just killed all my fish after just spending 2 grand on them a month ago.

Mabe redirect your filter and add a grow bed with plant-life to dissolve nitrates into your system. I dont understand why you would add nitrates to to treat a fish tank as thats what the fish produce i think that mabe your treating bore water.