The rectangle in question has been given with dimensions as follows;
Length = 7.4a - 4.4
Width = 8.4a + 7.5
The perimeter of a rectangle is derived as;
Perimeter = 2 [L + W]
Having been given the L and the W, we can now substitute for these into the formula shown above,
Perimeter = 2 [7.4a - 4.4 +8.4a + 7.5]
Perimeter = 2 [ 7.4a + 8.4a + 7.5 - 4.4]
Perimeter = 2 [15.8a + 3.1]
Perimeter = 31.6a + 6.2
