To model the total amount of water \( w \) that Martina used in her experiment, you need to multiply the amount of water in each container by the number of containers. Since she used 8.5 ounces of water in each of the 5 containers, the equation can be expressed as follows:
\[ w = 8.5 , \text{ounces per container} \times 5 , \text{containers} \]
To complete your equation, it would look like this:
\[ w = 8.5 , \text{ounces} \times 5 \]
So, to fill in your equation:
\[ w / = 8.5 * 5 \]
Thus, the total amount of water \( w = 42.5 \) ounces.