Assuming the ratio of 4:5 represents the ratio of width:length then we can set up a simple proportion to find the length...

L = 5(28)÷4
L = 35
Now we can find the perimeter and area of the rectangle:
A = LW
A = 28(35) = 980
P = 2L + 2W
P = 2(35) + 2(28) = 126