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
There are three kinds of statement that we could construct base on the given where as Vertical angels are congruent. First is converse: If angle 1 is 90 degree then angle 2 is 90. Second is Inverse: If angle 2 is not 90 then angle 1 is not. Third is Contrapositive: If angle 2 is not 90 then angle 1 is not 90 also.
Answer:
0.0081
Step-by-step explanation:
yes bye that's the answer
Step-by-step explanation:
Let x be the miles Kenyon ran on tuesday
Let y be the miles Kenyon ran on thursday
Given,
Mon + Tues + Wed + Thu = 8mi

also given,

Now we have x + y = 5.2 as equation 1 and -x + y = 0.4 as equation 2
Using equation 1,

Substitute this equation into equation 2.

Substitute y = 2.8 into equation 1.

Therefore Kenyon ran 2.4 miles on tuesday, and ran 2.8 miles on thursday.