Show that if a ≡ b (mod n) and c is a positive integer, then ca ≡ cb (mod cn)

If 3x+8=3x+8 is it one solution or no solution

A50% increase followed by 33 1/2% decrease

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”?