If I am understanding the question, and assuming the living room is a rectangle, then the border should be 80 ft
F = 1/2(r + 6.5)
2f = r + 6.5
r = 2f - 6.5
The 4 is the constant term.
For the five characters of the five-character password, the first three slots are already taken for the initial F, J, S, the password would become,
FJS_ _
The last two slots could be any of the even digits. In the fourth slot, Fiona can have any of the 5 values. On the fifth slot, she can have only 4 choices as the other digit was already used. Multiplying 5 and 4, the answer would be 20.
<span>the area of the circle :
r = 9\2
so :
S= r</span>² * Pi = (9\2)² * 3.14 = 63.58 cm²
