Answer:
length-x
width-x-4
area-- length* width
192=X*(X-4)
x^2-4x-192=0
x^2-16x+12x-192=0
X(x-16)+12(x-16)=0
(x-16),(X+12)
X= 16 because X cannot be negative like (-12)
the dimensions of the classroom will be
length = 16
width = 12
I hope this will help everyone