Solve each system by substitution -3x + 3y = 4 and -x + y = 3

If you could answer these your a life saver

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?

Using inductive reasoning, what are the next two number in this set? 2,3/2,4/3,5/4,