Please help, I can not figure out any of these questions.

Give all possible names for each angle shown. calculation tip: in angle abc, b is the vertex.

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

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?