The answer is 80 because all triangles equal 180
She made the mistake of grouping unlike terms and factorizing.
Given that
Helene is finding the sum (9 + 10i) + (–8 + 11i).
She rewrites the sum as (–8 + 11)i + (9 + 10)i.
We have to determine
Which statement explains the property of addition that she made an error in using?
According to the question
The mistake she did is in the second term distributing.
(9+10i) is not equal to (9+10)i
Similarly (-8+11i) is not equal to (-8+11)i.
The correct method she should have done is given below;
Grouping real terms together and imaginary terms together and finding the sum is,

Hence, she made the mistake of grouping unlike terms and factorizing.
To know more about Complex Number click the link given below.
brainly.com/question/10078818
Answer:
Graph C. Hope this is correct!!!
Step-by-step explanation:
He would use 9 bills, and 5 coins. (fours $10, one $5, four $1. three quarters, one dime, and one penny). I calculated it all to make sure the total came out as 49.86
Answer: B) 70.50
Step-by-step explanation: john is buying 3 tickets for each of 2 movies total : 6 tickets each ticket costs 11.75
so 11.75*6
= 70.50