<PRE><B>Question 41196</B>
Let the width of the frame be x.  Let the dimensions of just the picture be L and W.  Thus we know 
A = LW = 84
We also know that
(L + 2x)(W + 2x) = 240
We also know that
L + 2x = 20
W + 2x = 12
Let us solve these for L and W and plug in to the first equation, so we get
L = 20 - 2x
W = 12 - 2x
and then
(20 - 2x)(12 - 2x) = 84
240 - 64x + 4x^2 = 84
4x^2 - 64x + 156 = 0
x^2 - 16x + 39 = 0 
(x - 13)(x - 3) = 0
x = 13 or x = 3
but x cannot be 13, so
x = 3 </PRE>