What is a "real number"

are numbers which  include all the rational numbers, such as -3 which is an integer and the fractions such as 5/4, and all the irrational numbers, such as √7, and π

$4034.40

the perimeter of the field is the sum of the lengths of the four sides:

47 yd + 158 yd + 47 yd + 158 yd = 410 yd

the cost of 3 ft (1 yd) of fence is 3×$3.28 = $9.84.

so the cost of jake's wood perimeter fance is

(410 yd) × ($9.84 /yd) = $4034.40