The frame is four rectangles, two are (30+x) by x and two are (21+x) by x. So That simplifies to: Divide through by 2: Solve by the quadratic formula: Ignore the minus About x = 1.726273692 cm = width of frame. Round off as you were told. Edwin
The frame is the large rectangle minus the small rectangle. Let x be the width of the frame, so the large rectangle is 30+2x by 21+2x and the small rectangle is 30 by 21 or 630. So their difference must equal 188 That simplifies to: Divide through by 2: Solve by the quadratic formula: Ignore the minus About x = 1.726273692 cm = width of frame. Round off as you were told. Edwin