This is geometry. Please help explain this.

Write a story that matches with the expression 42x-5 pls hurry

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

What is the 17th term in the arithmetic sequence in which a6 is 101 and a9 is 83