let 'x' be the numerical value of the side of the square and x>=0

the are of the square is

A = x^2

the perimeter of the square is

P = 4x

the numerical value of the area of a square is 36 less than 3 times the numerical value of its perimeter

A = 3*p - 36

x^2 = 3*4x - 36

x^2 - 12x + 36 = 0

by solving the quadratic equation we find

x = 6

the perimeter is P = 4x = 4*4 = 16

the numerical value of the perimeter of the square is 16.