Answer:

Step-by-step explanation:
Given the fraction 
Consider its numerator and factor it:

You cann not take the cube root from
you can only take the cube root from
, then the smallest whole number
such that
is a cube number is

When 

So the ratio is 1 to 2 to 5
so basically 1 unit of soda water to 2 units of fruit punch to 5 units of ginger ale
total is 1+2+5=8 units
so 4 gallons=8 units
divide by 8
1/2 gallon=1 unit
soda water=1 unit=1/2 gallon
fruit punch=2 unit=1/2 times 2=1 gallon
ginger ale=5 unit=5 times 1/2=5/2=2 and 1/2 gallon
soda water=1/2 gallon
fruit punch concentrate=1 gallon
ginger ale=5/2 gallon or 2 and 1/2 gallon