In how many different orders can you line up 8 cards on a table?

The measure of one angle of an octagon is two times smaller that of the other seven angles. what is the measure of each angle?

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?

The roots of the function f(x) = x2 – 2x – 3 are shown. what is the missing number?