<PRE><B>Question 164585</B>
Let x=amount of water needed

Total weight of the mixture=10+5+5+x=20+x
And we are told that the water equals 25% of the mixture, so:

0.25(20+x)=x  get rid of parens (distributive law)
5+0.25x=x subtract 0.25x from each isde
5+0.25x-0.25x=x-0.25x  collect like terms
5=0.75x  divide each side by 0.75
x= 6.6667 or 6 2/3 kg----------------------amount of water needed

CK
20+6.6667=26.6667
0.25*26.66667= 6.6667
6.6667=6.6667

Hope this helps---ptaylor</PRE>