Answer:
2 1/4 yards above sea level
Step-by-step explanation:
The midpoint elevation is the average of the endpoint elevations, their sum divided by 2. When elevation is below sea level, it is represented by a negative number.
(17 3/4 - 13 1/4)/2 = (4 2/4)/2 = 2 1/4 . . . yards above sea level
2-3k because the difference between something means it is subtraction and the product of 3 and k would just be 3k since you don't know what k is.
9. 9.37, 9.3, 9.219, 9.129
10. 0.101, 0.100, 0.012, 0.001
11. 5.312, 5.231, 5.132, 5.123
12. 62.950, 62.905, 62.833, 62.383
Hope it helps