Answer: Jon will need to add 560 ounces of blue tint.
To find the correct amount, we should write and solve a proportion each time.
On the left side of the proportion, we will write our known rate (4 Red / 28 Blue).
On the right side of the proportion, we will write the amounts we are looking for.
We can write and solve the following equation.
4 Red / 20 Blue = 80 Oz Red / ? Oz Blue
If you cross multiply and divide the proportion, you will need 560 ounces of blue tint.