9514 1404 393
Answer:
border area = 6x +126
Explanation:
The dimensions of the picture with its frame will be ...
(15 +2×3) long by (x +2×3) wide
The border area is the difference between the picture overall frame area and the picture area:
border area = (15+6)(x+6) -(15x) = 21x +126 -15x
border area = 6x +126