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
For this case we have to:
x: Let the variable representing the number of people to travel in the group
y: Let the variable representing the number of miles traveled.
If friends only have $22 then we have the following inequality:

Now, if there are three people in the group we have that 

The taxi can travel a maximum of 19.33 miles.
On the other hand, if the group wants to travel 10 miles then we have to y = 10.

Thus, they could travel a maximum of 5 people.
ANswer:

Traveling 3 people, the taxi can travel a maximum of 19.33 miles
Traveling 10 miles, a maximum of 5 people can travel
Answer:
h=8
Step-by-step explanation:
the goal is to isolate the variable, get it all by itself. to do that in this problem, we have to move the -7/8 away from the h. we do this by multiplying by the reciprocal (the opposite of the fraction). The reciprocal of -7/8 is 8/-7. So multiply both sides by this and you will get h=8