Answer:
a) 
And if we solve for
we got:

b) False
The reason is because we don't satisfy the following relationship:

We have that:

c) False
In order to satisfy independence we need to have the following condition:

And for this case we don't satisfy this relation since:

Step-by-step explanation:
For this case we have the following probabilities given:

Part a
We want to calculate the following probability: 
And we can use the total probability rule given by:

And if we solve for
we got:

Part b
False
The reason is because we don't satisfy the following relationship:

We have that:

Part c
False
In order to satisfy independence we need to have the following condition:

And for this case we don't satisfy this relation since:
