Can someone explain how to do these and help a brotha

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”?

Which of these angles are supplementary? a. 100o and 90o b. 78o and 102o c. 54o and 146o d. 12o and 78o

Ineed the solution to this problem and the steps.