Final answer:
The expression to calculate the cost per week to keep 8 adults of your animal at the zoo is 56x.
Step-by-step explanation:
The cost per week to keep the 8 adults of your animal at the zoo can be calculated by multiplying the amount of food one adult eats in a day (represented by x) by the number of days in a week (7). Therefore, the expression to show the cost per week is 8x*7. Simplifying this expression, we get 56x.