To find out how much protein powder Moira added to her smoothie, we can start by adding together the weights of the other ingredients.
The ingredients she added are:
- Water: 320 grams
- Oatmeal: 80 grams
- Mango: 100 grams
Now, we add these weights together:
\[ 320 , \text{grams} + 80 , \text{grams} + 100 , \text{grams} = 500 , \text{grams} \]
The total weight of the smoothie is given as 520 grams.
Now we can find the weight of the protein powder by subtracting the total weight of the other ingredients from the total weight of the smoothie:
\[ 520 , \text{grams} - 500 , \text{grams} = 20 , \text{grams} \]
Thus, Moira added 20 grams of protein powder.