Answer:
Each cereal bar is 1.4 ounces
Subtract the weight of the empty box from the 18.55 (because that's the weight of the box AND the cereal)
You are then left with 16.8 ounces, which is just the weight of the 12 cereal bars.
To find the weight of one cereal bar, assuming that all cereal bars weigh the same, you need to divide 16.8 by 12.
So that results in each cereal bar weighing 1.4 ounces