How is adding 21.39 + 21.59 like adding 2139 + 2159?

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 statement accurately describes how to perform a 90° clockwise rotation of point a (1,4) around the origin?

Peter measures the angles in a triangle. he finds that the angles are 95, 10 and 75. is he correct? explain your answer