The equation is represented by:
0.5 + 10b + 4 = 19.5
In which 19.5 is the total weight of the box and it's contents.
0.5 is the weight of the cardboard box.
4 is the weight of the jar of peanut butter.
10b is the weight of all loaves of bread.
And b is the weight of a single loaf of bread
The answer is:
The solution of the equation, which is the value of b, represents the weight of a single loaf of bread.