Both coconut oil and lavender need to be added to a body wash. One unit of coconut oil takes 0.7 minutes to be effective while one unit of lavender takes 0.9 minutes to be effective. The body wash must contain at least 300 units of coconut oil and at most 550 units of both ingredients. Since too much coconut oil can make the body wash too oily, there can be at most thrice the amount of coconut oil as lavenders in the body wash. How many units of each should be added to the body wash to minimize the total amount of time it takes for the mixture to be effective? (Note: one must be added before the other)