Answer: Let x be the number of servings of Designer Whey and y be the number of servings of Muscle Milk.
We know that:
x + y = 7 (because you want 7 days of supply)
And the protein content per serving of Designer Whey is 18g and the protein content per serving of Muscle Milk is 20g. So:
18x + 20y = 412 (because you want 412g of protein)
And the carbohydrate content per serving of Designer Whey is 4g and the carbohydrate content per serving of Muscle Milk is 8g. So:
4x + 8y = 108 (because you want 108g of carbohydrates)
We can now use the above two equations to solve for x and y. We'll start by solving for x in terms of y:
18x + 20y = 412
18x = 412 - 20y
x = (412 - 20y)/18
Now we can substitute this expression for x into the equation for the carbohydrates:
4x + 8y = 108
4((412 - 20y)/18) + 8y = 108
1664 - 80y + 8y = 1080
1664 = 1080 + 80y
584 = 80y
y = 7.3
Since y must be an integer, we'll round it down to 7. So y = 7. We can now use either equation to find x:
18x + 20y = 412
18x + 20 * 7 = 412
18x = 412 - 140
18x = 272
x = 15.1
Since x must be an integer, we'll round it up to 15. So x = 15.
Therefore, you should combine 15 servings of Designer Whey and 7 servings of Muscle Milk in order to meet your requirements.
Explanation: