7. Three rectangles are placed mutually adjacent and without gaps or overlaps to form a larger rectangle. One of the three rectangles has dimensions 70 by 110 . Another of the rectangles has dimensions 40 by 80 . What is the maximum perimeter of the third rectangle?
7. 300

There are essentially four different configurations as shown in the diagram. The perimeters of the third rectangle in these configurations are 220,240,300 and 140 respectively. Therefore the maximum possible perimeter of the third rectangle is 300 .