$A_T = 400000 km^2$
$K_T = 490$
$N = 7$
$R = 60km$
$C = \ ?$
$A_C = \pi R^2 = \pi * 60^2 = 3600\pi$
$NM = \cfrac{A_T}{A_C} = \cfrac{400000}{3600\pi} = 36$
$K = \cfrac{K_T}{N} = \cfrac{490}{7} = 70$
$C = MNK = 36*70 = 2520$
$P_{RX} = 54 dBm$
$P_{TX} = 6W$
$G_{RX} = G_{TX} = 20 dB$
$f = 2.4GHz$
$M = 5$
$K = 7$
$C = 2500$
$D = \ ?$