Answer: C) 75% 
Explanation:
Let G represents the event of having garbage in houses and F represents the event of houses having fenced in backyard.
Given: In neighborhood , the probability of houses have a garage and a fenced in backyard 

The probability of houses have a garage P(G)=80%=0.8
The probability that a house has a fenced in backyard given that it has a garage is given by :-

In percent, 

Hence, the probability that a house has a fenced in backyard given that it has a garage = 75%.