So,
Here we have the following table:
We want to find the probability to choose a man. So, there are 7+21 = 28 men in total.
The total number of people is 70, so this probability is:

b) The probability that the person is a man who doesn't practice sport.
If we look at the table, there are 7 men who doesn't practice sport, so:

7/70 = 0.1, so this probability is 0.1
c) Finally, remember that:

We want the to find the probability that the person doesn't practice sport given that it is a man.
If we replace:
