Each of the 20 people has 19 other people to communicate to. If you add that all up you get 20*19 paths, but then each path is counted twice (back and forth), so we divide this by 2. 20*19/2 = 190.
The general forumula is n(n-1)/2
I think the first one is All of the above
"To move an icon, you right-click it and select “Pin to start menu.” True False"
False
802.11 is a Wi-Fi standard, not a frequency, both of those operate at 2.4 GHz. Bluetooth operates at frequencies between 2402 and 2480 MHz, or 2400 and 2483.5 MHz.
