Using the z-distribution, as we are working with a proportion, it is found that the margin of error for the 90% confidence interval is of 0.0524 = 5.24%.
<h3>What is a confidence interval of proportions?</h3>
A confidence interval of proportions is given by:

In which:
is the sample proportion.
The margin of error is given by:

In this problem, the critical value is given as z = 1.645, and since 26 out of 80 students said they would be willing to pay extra:

Then, the <em>margin of error</em> is of:

More can be learned about the z-distribution at brainly.com/question/25890103
First make sure that one of the variable has the same coefficient in each equations.
For example lets use:
y=x+3
2y=3x-1
Since neither the y's or x's are the same, we must multiply the equations to make them the same. I am going to multiply the first equation by 2 so I can eliminate the y's.
So we get:
2y=2x+3
2y=3x-1
Then we subtract the second equation from the first to eliminate the y's. So we end up with 0=-x+4 and now we solve for x
0=-x+4
x=4
Now we plug in our x into either original to get the y-value. I am using the first
y=x+3
y=4+3
So the x=4 and y=7
Hope this helps!
Answer:
P= 26
Step-by-step explanation:
-8
f(x) is y, in which x is the independent variable
when x = 5, y = -8