Answer:
a) 
With:


b) 

c) 

d) 


Step-by-step explanation:
For this case we know the following propoertis for the random variable X

We select a sample size of n = 81
Part a
Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

With:


Part b
We want this probability:

We can use the z score formula given by:

And if we find the z score for 89 we got:


Part c

We can use the z score formula given by:

And if we find the z score for 75.65 we got:


Part d
We want this probability:

We find the z scores:



Linear pair angles are always supplementary.
So,
(2x+10) +(3x+10) = 180
5x+20 = 180
5x =180-20
5x=160
x= 160/5
x=32
Hence, the angles are 74 & 104
Yes. I need at least 20 characters for this to be an answer so I'm typing this to answer your question