Answer: f(x) = 195 - x*5
Explanation:
Colton has 120 small prizes and 75 larger prizes.
Then at the start, he has 120 + 75 = 195 prizes.
In each bag, he puts 3 small prizes and 2 larger prizes, then in each bag there are 3 + 2 = 5 prizes.
Then if he fills x bags, he will have: x*5 fewer prizes, then we can write the equation f(x) as:
f(x) = 195 - x*5
Where when x = 0, this means that he filled zero bags, then he has the initial amount of prizes, 195.