AGHH need help please, i’m stuck

Anormally distributed data set has a mean of 176.3 and a standard deviation of 4.2. what is the approximate z-score for the data value of 167.9? 2.00 −2.00 8.4 −8.4

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.