Answer:

And we want to find the following probability:

And for this case we can use the cumulative distribution given by:

And for this case if we use this formula and the complement rule we have:

Step-by-step explanation:
Let X the random variable who represent the pizza delivery time and we know that the distribution for x is given by:

And we want to find the following probability:

And for this case we can use the cumulative distribution given by:

And for this case if we use this formula and the complement rule we have:

F(x) is what they gain, and g(x) is what they lose. Therefore, it would be (f-g)(3) or first choice
The answer to this would be 6