Answer:
20% conditional probability that I am not working, if I am at my office
Step-by-step explanation:
Conditional probability formula:

In which
P(B|A) is the probability of event B happening, given that A happened.
is the probability of both A and B happening.
P(A) is the probability of A happening.
In this question:
Event A: Being at the office.
Event B: Not working.
I am at my office AND not working 2% of the time.
This means that 
I am at my office 10% of the time.
This means that 
What is the conditional probability that I am not working, if I am at my office?



20% conditional probability that I am not working, if I am at my office