Simplify. Use a vertical format.
(x2 − 6x + 9) − (2x2 − 6x + 8)

Two lines that do not intersect are skew. always sometimes or never

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?

With number 11 ( show how you got the answer)