in a test consisting of 90 questions, Ama answered 75% of the first 40 questions correctly. If she had to get a score of 80% in
the test, (i) how many questions did she answer correctly out of the first 40 questions? (ii) how many questions should she answer correctly out of the 90 questions? (iii) what percentage of the remaining 50 questions should she answer correctly in order to get the 80%?
Vertical lines have undefined (or no) slope always, so this is a true statement. To see why, look at a horizontal line (which is perpendicular). They have zero slope. That comes from the y = mx + b slope intercept form and their equation being y = b, and b is some number.
