Total milk by adding x gallons of grade 1 , y gallons of grade 2 and z gallons of grade 3 = x/100 + 2y/100 + 3y/100
Total solution is 1.5 milk. So milk in the total solution = (x+y+z)*1.5/100
These two quantities are equal.
So x + 2y + 3z = 1.5(x+y+z). Solving this we get x = y+3z
SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008