Answer:
Initial number of trees were 204.
Step-by-step explanation:
555 must be a typo error. The question will not produce correct answer. I worked out with 55 but the answer is wrong. So, the number is 5.
Lets say MacDonald removed 5 orange trees from his farm.
Let t be the initial number of trees
After removing 5 trees, the remaining left are t-5 trees
As given - Each of the remaining trees produced 210 oranges for a total harvest of 41790 oranges. This means

Solving for t:



t = 204
So, initial number of trees were 204.
We can check this : 

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Working with 55 we get the wrong answer:



t = 144
We can check this : 
(wrong)
Answer:
a. 18 b. 119°, 118°
Step-by-step explanation:
a. Given angles are vertical, so they are equal.
6a+11 = 2a+83
6a-2a = 83-11
4a = 72
a = 72/4
a = 18
b. Substituting the value of a in the given angles,
6a+11 = 6*18+11 = 108+11 = 119°
2a+83 = 2*18+83 = 36+83 = 118°
No because it fails the vertical line test hope it helps