Answer:20 ounce
Explanation
Given
2 parts Grape juice is present in 6 parts of water
Let us suppose Grape part be g and water part be w in the mixture
Also it is given 80 ounce of grape Juice is needed to make
thus
g+w=80
also grape to water ratio is



Substituting values
we get

w=60 ounce
thus grape is 20 ounce