Answer:
10 in
Step-by-step explanation:
Let x be the width of the mat width showing around the picture. Since the sheet is 20 in wide by 15 in high, and the perimeter of the mat is 110 in. We have the following equation:
2*(20 + x + 15 + x) = 110
35 + 2x = 55
2x = 20
x = 20/2 = 10 in