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
The given details are illustrations of addition and subtractions of fractions. The scuba driver is at an elevation of
ft below the sea level.
Given that:
--- the first dive
---- the additional dive
From the question, we understand that the diver starts at the sea level.
This is represented with 0ft.
So, the diver's elevation (d) is calculated as follows:
--- we use subtraction because the diver is below the sea level
So, we have:


Convert fractions

Take LCM


Reduce fraction

The above value means that the diver's elevation is at
ft below the sea level.
Read more about fractions at:
brainly.com/question/18134643
Answer:
in my opinion I think the answer is a because I don't know why
Step-by-step explanation:
4/3 or 1.3333 or 1 1/3 they are the same thing just in varies forms