We have just received 25 litres of an antimicrobial solution that is to be added to the hens drinking water, but the solution that we have is 31% of the concentrate, whereaswe require it to be 28%.

My question is this... If I have 1 litre of concentrate at 31%, how much water must I add to this in order to bring this down to the specified 28% concentration?

This was an error on the manufacturers side, and as I am not mathematically equipped any help from you guys would be much appreciated!

Kind regards,

Adam H