another sequence is 19/480
C = 36 pi units = 2 pi r. Thus, r = 36 pi / (2 pi) = 18 units.
Thus, A = pi*r^2 = pi*(18 units)^2
4y - 5x = 9
x = 4y + 11
We can substitute this value of x in the first equation:
4y - 5(4y+11) = 9
4y - 20y - 55 = 9
16y = -64
y = -4
x = 4y + 11
x = -16 + 11
x = -5