Hello!
We don't need to find the exact perimeter of the fencing, just an estimate. 
We will round 12 ft 3 in to 12 ft, because it is closer to 12 ft than 13 ft. 
We will also round 8 ft 11 in to 9 ft because there are 12 inches in a foot, which makes 9 ft closer. 
The formula for perimeter of a rectangle is: 
P = 2l × 2w
The length is about 12 feet and the width is about 9 feet. 
Substitute the length and width: 
P = 2(12) + 2(9)
Solve: 
P = 24 + 18 
P = 42 
Jose will need about 42 feet of fencing.