Answer:
She makes 7.8% portion of sales collectively.
Explanation:
Let us assume she makes total of 100 calls.
The percentage of calls which are busy or unanswered = 22 %
So, now calculating 22% of 100 , we get:

So, 22 of her calls are UNANSWERED.
Now, let us find out the number of calls successfully made by telemarketer.
Total successful calls = Total Calls made - Number of unanswered calls
= 100 - 22 = 78
So, she makes a total of 78 calls successfully.
Now, he sells subscriptions to 10% of the 78 calls made successfully.
So, now calculating 10% of 78 , we get:

So, she sold 7.8 subscriptions in total out of 100 attempts.
Also, as we know 7.8 out of 100 = 7.8% of 100.
Hence, she makes 7.8% portion of sales collectively.