Answer:
84
Explanation:
The equation that models this situation is 1110 = 15x + 150 where x = cameras sold (note that this doesn't include the first 20 cameras, we'll add those on at the end). Let's solve for x!
1110 = 15x + 150
960 = 15x
x = 64 so the answer is 64 + 20 = 84 cameras.