Question

(How Much Water must be added to 20 liters of 50% alcohol solution to Dilute it to 10%)

Answer 1

a + b = t ; *-x
xa + yb = zt


-xa -xb =-xt
xa+yb = zt
------------
b(y-x)= t(z-x)

b@y = t(z-x)/(y-x) maybe

Answer 2

water@0 = 20(.50 - .10)/(0-.10); chop off the negative and se if it works :)

Answer 3

i get 80, maybe

80(0) + 20(.50) ?= 100(.10)

0 + 10 ?= 10 yep