Check the picture below.
and since a triangle has a sum of 180° for all interior angles.
A = 180 - 39.34 - 25
A = 115.66

make sure your calculator is in Degree mode.
Answer:
Step-by-step explanation:
given that certain tubes manufactured by a company have a mean lifetime of 800 hours and a standard deviation of 60 hours.
Sample size n =16
Std error of sample mean = 
x bar follows N(800, 15)
the probability that a random sample of 16 tubes taken from the group will have a mean lifetime
(a) between 790 and 810 hours,
=
(b) less than 785 hours

, (c) more than 820 hours,

(d) between 770 and 830 hours
=
Triangle ABC is translated 3 units right and 2 units up
by looking at point A (-4,5) which is translated to A'(-1,7)
we can tell by looking at the points that -4 is shifted by 3 units to the right ti reach -1 and 5 is shifted upwards by 2 units to reach 7