line N has slope m = 
given a line with slope m then the slope of a line perpendicular to it is
= - 
thus line N has slope -
= 
Answer:
Let the scores on the first two test be x
Let score for third test be 14 exceeds second( or first) = x + 14
Total = 233
x + x + (x + 14) = 233
3x + 14 = 233
3x = 219
x = 73
Score of the third test = x + 14 = 73 + 14 = 87
Therefore, the scores are 73, 73, 87
Answer with explanation:
Class Interval Variate Frequency
16-18 16 1
19-21 0 0
22-24 0 0
25-27 26,27 2