A certain shade of pink is creating by adding 3 cups of red paint to 7 cups of white paint.
Since, 7 cups of white paint are added with 3 cups of red paint.
We have to determine that how many cups of red paint should be added to the paint when 1 cup of white paint is being added.
We will use unitary method to solve this problem.
So, 1 cup of white paint should be added with 
 cup of red paint to create pink paint.
 cup of red paint to create pink paint.
Therefore, 
 cup of red paint is added with 1 cup of white paint.
 cup of red paint is added with 1 cup of white paint.