9x + 5 = 68
9x = 63
x = 7
Cole put seven books on each shelf.
Answer:
128.67 ft
Step-by-step explanation:
Let the height of the tower be x feet.

43.7 % is equivalent to 0.437 .
X = 7/3
Because 16^1.66667 = 101.593 and 4^3.33333 = 101.593
Let d(x) = 2x - 4
Or
y = 2x - 4
We have replace x = y
x = 2y - 4
Now Isolate "y"
x + 4 = 2y
Pass "2" dividing
(x + 4) / 2 = y
y = x/2 + 2
Or
d(x)^-1 = x/2 + 2