What multiplies to 6, but adds to 9

Complete the equation of the line through (−10,3) and (−8,−8). use exact numbers.

Bring the fraction a/a-4 to a denominator of 16-a^2

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”?