Answer:
So he will need 168 feet of fencing.
Step-by-step explanation:
The perimeter formula of a rectangle is P=(2xL)+(2xW)
The length is 12 and the width is 9.
First, do P=(2x12)+(2x9), P=24+18 P=42 feet
Next, since there are four pens multiply the perimeter of 1 pen by 4.
4x42=168 feet of fencing
So, Don will need 168 feet of fencing.