a.)perimeter of any window with a length of 5 ft, given the width., just substitute the the length to given function
P = 2l + 2w
P = 2(5) + 2w
P = 10 + 2w
b.)perimeter of any window with a width of 3 ft, given the length. do the same thing but substitute it to the w
P = 2l + 2w
P = 2l + 2(3)
P = 2l + 6