8.5 = x/4 (this is a fraction)

x = 8.5 * 4

x = 34

x−16.1 = 5.2

x = 5.2 + 16.1

x = 21.3

10 = + 8 + s

10 = 8 + s

s = 10 - 8
s = 2

−5 = s − 9

s = -5 + 9

s = 4

9s = 36

s = 36 / 9

s = 4

8s = 8