Answer:

Step-by-step explanation:
Given: The ratio of cups of sparkling water to cups of grape juice concentrate is
in a recipe for fizzy grape juice.
To find: two more ratios of cups of sparkling water to cups of juice concentrate that would make a mixture that tastes the same as this recipe
Solution:
Equivalent ratios are the ratios that have the same value.
Find two ratios equivalent to 
Multiply both numerator and denominator of
by 2

Multiply both numerator and denominator of
by 3

So, two more ratios of cups of sparkling water to cups of juice concentrate that would make a mixture that tastes the same as this recipe are 
I think is 20 but i am not sure
Step-by-step explanation:
you are "hiding" some more information (like how much they made together).
without that we cannot calculate the actual values.
all I can do is set up the equations expressing the given relations between the parts of the total :
a = amount Alberto made
b = amount Benjamin made
c = amount Carlota made
b = 3×a
c = 2×b = 2× 3×a = 6×a
that's it.
your see ? now we need something that "ties" all 3 together, an equation of all 3 variables, where we can use the first 2 equations (by substitution) and then solve for the remaining third variable.
and that is missing.
if it is something like "together they made x", then we would have
a + b + c = x
a + 3a + 6a = x
10a = x
a = x/10
b and c we get then from the first 2 equations by simply using the calculated value of a :
b = 3×(x/10) = 3x/10
c = 6×(x/10) = 6x/10 = 3x/5