I believe the answer is C
The grade on the west side would be the vertical rise divided by the horizontal run or 525 divided by 800' or rounded off to 66% (a steep grade as in an underground mine a grade of 25% is considered very steep for vehicles to go up or conveyors to travel). On the east side the 40% grade was obtained by dividing the 525' vertical height by the 1300' run.
Math I hate math bc it sucks
3 as in 3 layers of skin is that what you were talking about hope this helps plus the 1 layers is epidermous 2 is dermis and 3rd is tissue
The series is 84(1+1/5+1/25+...)=84(1/(1-1/5)=84÷4/5=84×5/4=21×5=105. Upper limit is 105.