Question 975146
(i) the amount of juice = 90% x 5litre = 4.5 Litre 
    the amount of water = 10% x 5 litre = 0.5 litre

(ii)amount of water added = x litre 
    so total quantity of drink = (5+x)litres
    ratio of juice to total water = 4.5 / (x+0.5) 
    
    4.5 / ( 5 + x) = 75%

(iii) 4.5 = (5+x) 3 /4
      4.5 X 4 = 15 + 3x
      solving this gives  x = 1 litre