To find the mean (average), we first need to add up all the test scores (14 + 19 + 19 + 20 + 16 + 18 + 15 + 17 + 12 = 150). Then, we need to divide that number (150) by the number of numbers in the data set (9 in this case). So the mean of these test scores is about 16.6666666667.
The answer is 60 because were subtracting in the equation but to find m we need to the opposite which is to add 53 plus 7 which is 60. To check your answer do 60-7 equals 53