Answer:
a) Probability that Julia misses two shots in a row = 
b) We can use the complement rule on this case. Let X the number of shoots successful, we want this probability:

And using the complement rule we have this:

And P(X=0) correspond to the probability that Julia misses two shots in a row founded on part A so then we have:

Step-by-step explanation:
Part a
For this case we know that Julia enjoys shooting paper balls into the basket across her office.
She misses the first shot 50% of the time.
Probability that Julia misses the first shot = 
When she misses on the first shot, she misses the second shot 20% of the time.
Probability that Julia misses the second shot = 
For this case we need to find the probability of missing two shots in a row
So we can multiple the two probabilities like this
Probability that Julia misses two shots in a row = 
Part b
For this case we want probability of making at least one successful throw
And we can use the complement rule on this case. Let X the number of shoots successful, we want this probability:

And using the complement rule we have this:

And P(X=0) correspond to the probability that Julia misses two shots in a row founded on part A so then we have:
