The graph of which function has an axis of symmetry at x = 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?

How to write four times a number,minus 6,is equal to theee times the number+8 as an equqtion

Use sigma notation to represent the following series for 9 terms.