Explain the difference in meaning between 1-3 and -3

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?

Solve: 25 points find the fifth term of an increasing geometric progression if the first term is equal to 7−3 √5 and each term (starting with the second) is equal to the difference of the term following it and the term preceding it.

(fog)(x) if f(x)=x^2- 4 and g(x)=x^2 + 2 x, f(g(x))= f(x^2+2x) (x^2+2x)^2-4 (x^2+2x)(x^2+2x)-4 (x^4+2x^3+5x+4x^2)-4 x^4+2x^3+4x^2+5x-4 what am i doing wrong