It Is Currently Neutral because if you're 35 ft. Underground and you raise 35 feet it 0 you're ground level
S is slope
S= rise/run
S1=3/12=1/4
S2=2/16=1/8
S3=5/15=1/3
S4=4/20=1/5
Deepest slope S3 aka C
The answer to this question is 29
You distribute the negative in the second equation