Question 37543
Here the setup for this is 
(40 - 2x)(24 - 2x) = 192
4x^2 - 128x + 960 = 192
4x^2 - 128x + 768 = 0
x^2 - 32x + 192 = 0
(x - 8)(x - 24) = 0
x = 8 or x = 24
but x = 24 is extraneous, x = 8
Therefore the dimensions of the original picture are
(40 - 16) by (24 - 16) or
24 in x 8 in