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:
$41.0625
Step-by-step explanation:
Divide $054.75 by 4
Multiply the answer to that (13.6875) by 3 or subtract 054.5 by 13.6873
The answer to that step is your answer.
Answer:
1440
Step-by-step explanation:
Hope it helps!
Here are the log properties you need:
We are given one angle is 3 times less than other.
Let us assume one angle measure is x degrees and another is 4x.
Because x is 3x less than 4x. ( We can check 4x-x= 3x)
Sum of complementary angles is 90 degrees.
So, we can setup an equation
First angle measure + first angle = 90 degrees.
x+4x = 90.
Adding x and 4x, we get 5x.
So, 5x = 90.
Dividing both sides by 5, we get
5x/5 = 90.
x= 18.
So, one angle is of 18 degrees.
Another angle = 4x = 4 times 18 = 72 degrees.
So, required angles are of 18 degree and 72 degree.