Florence flask has 500 grams of a 72% salt solution. How much water must be added to obtain a 25% salt solution

ooh, fun

find what 72% of 500 is to find how much salt is in there

72% of 500=0.72*500=360g salt

note that 25%=25/100=0.25

if we add x grams of water, then the proprtion wil match

salt/total=25%

360 / (500+x) = 0.25

multiply both sides by (500+x)

360=0.25 (500+x)

divide both sides by 0.25

360/0.25=500+x

minus 500 from both sides

(360/0.25) - 500=x

1440-500=x

940=x

you must add 940 grams of water