Kilograms per cubic centimeter
7 x - 5 = 8
7 x = 8 + 5
7 x = 13
x = 13/7
7 ( 13/7) - 5 = 8
91/7 - 35/7 = 56/7
56/7 = 56/7 = 8
S = r·α is the formula to find the arc length (s), given the radius (r), and angle measure (α) in radians.
If the angle measure is NOT given in radians you must convert to radians.
s = 8 · 2.6
s = 20.8 in
The first one is correct.
