Final answer:
Using an algebraic equation, we find that Jack caught 12 fish, as Naomi caught half as many fish as Jack and together they caught 18 fish.
Step-by-step explanation:
This problem is a classic example of a simple algebraic relationship. Let's use variables to represent the number of fish each person caught. Let's use J to represent the number of fish Jack caught. According to the problem, Naomi caught half as many fish as Jack. We can represent this as 0.5J. Adding the number of fish Naomi caught to the number Jack caught gives us the total number of fish, which we know is 18.
To find the solution, we can set up the following equation:
J + 0.5J = 18
Combining like terms gives us:
1.5J = 18
To find the value of J, we divide both sides by 1.5:
J = 18 \/ 1.5
J = 12
So, Jack caught 12 fish, which makes the correct answer C.12.