Which lines are parallel

Triangle xyz has vertices x(1,3), y(0,0)

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 8

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?