Please help me with these problems:

$1.$ For a satellite communication channel, the uplink C$/$No ratio is $80$ dB$/$Hz and the downlink value is $90$ dB$/$Hz$.$ Solve the overall C$/$No ratio in dB$/$Hz$.$

$2.$ What is the isotropic receive level at an earth terminal antenna where the free space path loss to the associated satellite is $196\mathrm{.}4$ dB and other link losses are $2\mathrm{.}6$ dB$?$ The satellite EIRP is $34$ dBW$.$

$3.$ Company X has $10$ employees, each placing an average of $20$ minutes of long distance calls per day. The average call lasts $5$ minutes. It has been determined that $20\%$ of the calls are made during the busy hour. A total of $4$ external phone lines are used to place the pool of calls. Solve the traffic intensity in Erlang during the busy hour.