You can
put this solution on YOUR website!
I AM ASSUMING THAT THE "i" SHOULD BE A "1"
Let x=amount of water needed
Now we know that the amount of pure antifreeze that we have before the water is added (1 gal) has to equal the amount of pure antifreeze that we have after the water is added(0.60(1+x)). So our equation to solve is
1=0.60(1+x) get rid of parens
1=0.60+0.60x subtract 0.60 from each side
1-0.60=0.60-0.60+0.60x collect like terms
0.40=0.60x divide each side by 0.60
x=2/3 gal-------------------------amount of pure water needed
CK
1=0.60(1 2/3)
1=0.60(5/3)
1=0.20*5
1=1
Hope this helps---ptaylor