first you have to find the triangle, then you can move to the actual question.
x+30+80 = 180
x+110 = 180
x+110 - 110 = 180-110
x =70
now you can go to the actual question.
y + 70 = 180
y+70- 70 = 180-70
y = 110
there is your answer. hope this is helpful
I'm not sure where it starts and ends
Answer:

Step-by-step explanation:
Part A ;

Part B ;

I=√-1 and all the steps are there
Answer:
frequency= 165Hz
period= 
Step-by-step explanation:
1. To calculate the frequency using the formula:
f = v/λ
where,
f=frequency (what the question asked)
v=speed of wave (given in the question=330m/s)
λ=wavelength (given in the question=2m)
SO,

= 165Hz
2. To calculate the period use the formula:
since 
therefore, 
where,
f= frequency (what we solved above=165Hz)
T= period (what the question asked)
SO,
