Question 1057404
Let t be the thickness of the frame. Then:
(20-2w)(14-2w)=148
280-68w+4w²-148=0
4w²-68w+132=0
Using the quadratic formula,{{{w = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} , we get two roots: 14.7649820431 and 2.23501795693. The most sensible choice is that the frame is 2.23501795693 in. thick. ☺☺☺☺

If 232 sq. in. are showing, then:
(20-2w)(14-2w)=232
280-68w+4w²-232=0
4w²-68w+48=0
w²-17w+12=0
Using the quadratic formula, i.e. {{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}, we get two roots: 16.2620873481 and 0.73791265187. The only logical choice is a frame that is 0.73791265187 in. in thickness. ☺☺☺☺