The percent of the drink is juice is:
75%
It is given that:
A mom mixes 9 ounces of juice with 3 ounces of water.
This means that the total ounces of drink= 9+3 = 12 ounces.
The percent of the drink which is juice is:
Ratio of the quantity of juice to the total quantity of drink and multiplying this obtained quantity by 100.
i.e.
[tex]\text{Percent of the drink is juice}=\dfrac{9}{12}\times 100\\\\\text{Percent of the drink is juice}=75\%[/tex]