The piecewise function is given to be:

QUESTION A
For a 2 line ad, the first equation will be used. Therefore:

For a 3 line ad, the first equation will be used. Therefore:

Therefore, the difference is:

The difference is 0.
QUESTION B
For a 10 line ad, we will use the second equation:

At x = 10,

The cost of a 10 line ad is 108.
QUESTION C
For an 11 line ad, we will use the second equation.
At x = 11,

The cost of an 11 line ad is 117.