Answer:
D
Explanation:
Double the first equation. Write the second below it. Rearrange the second.
2x - 20 = - 4y
<u>-2x -16= +4y</u> Add.
- 36 = 0
There is no solution to this pair of equations.
The kind of ROI Luis demonstrates is : Positive ROI
<h3>Positive ROI</h3>
A positive ROI is defined as when the cost of a financial decision/step is lower than the gain of a financial decision.
Luis takes a loan to help him earn a certificate, the certificate he earns has helped him earn a good salary job which he can use to repay the loan.
Therefore in the long term Luis will have a positive return on investment on his financial decision.
Hence we can conclude that the kind of ROI Luis demonstrates is Positive ROI.
Learn more about ROI here : brainly.com/question/23603222
The probability that students who were randomly selected studied for the test, if they pass it with a B or higher grade is: D. 0.80.
<h3>How to calculate the probability?</h3>
In this exercise, you're required to determine the probability that students who were randomly selected studied for the test, if they pass it with a B or higher grade. Thus, we would apply Bayes's theorem.
- Let S represent studied for.
- Let B represent a score of B or higher grade
Therefore, we need to find P(S|B):
S|B = 0.80.
Read more on probability here: brainly.com/question/25870256
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<u>Complete Question:</u>
At the beginning of the semester, a professor tells students that if they study for the tests, then there is a 55% chance they will get a B or higher on the tests. If they do not study, there is a 20% chance that they will get a B or higher on the tests. The professor knows from prior surveys that 60% of students study for the tests. The probabilities are displayed in the tree diagram.