How do you work out a lookup and an if function on an excel spreadsheet?

Anetwork security application that prevents access between a private and trusted network and other untrusted networks

What is the total resistance in a circuit that contains three 60 ohm resistors connected in a series? a. 20 ohms b. 120 ohms c. 60 ohms d. 180 ohms

An english teacher would like to divide 8 boys and 10 girls into groups, each with the same combination of boys and girls and nobody left out. what is the greatest number of groups that can be formed?