We can assume that the shape is a rectangular prism by the given dimensions
Volume of a rectangular prism
Volume = Area of Base × Height of prism
= Length × Width × Height of prism
Substitute!
168 = L × 7 × 3
168 = L × 21
Divide 21 on either sides to isolate L

=

21 and 21 cancels out
8 = L
L = 8 yd
4b + 22 = 5 (b + 4) - 1 (remove the parantheses)
4b + 22 = 5b + 20 - 1 (calculate)
4b + 22 = 5b + 19 (move the terms)
4b - 5b = 19 - 22 (collect like terms and calculate)
-b = -3 (change the signs)
<em>b = 3</em>