Both sulfate and ginger need to be added to a shampoo. One unit of sulfate takes 0.5 minutes to be effective while one unit of ginger takes 0.75 minutes to be effective. The shampoo must contain at least 100 units of sulfates and a total of 400 units of both ingredient. Since too much sulfate can damage the hair, there can be at most twice the amount of sulfate as ginger in the shampoo. How many units of each should be added to the shampoo to minimize the total amount of time it takes for the mixture to be effective? (Note: one must be added before the other)