It would be C!!!!!!!!!!!!!!!
X = 180 - 58 - y
Y = 180- 126= 54
X= 180 - 58 - 54
X= 180- 112= 68 degrees
To calculate the mean, you must add all the numbers together and then divide by the total amount of numbers there are.
The mean score of all these numbers would be 80.875, or 80 rounded to the nearest hundredth.
The Associative Property of Addition.