Help pls!! and no links either :)

Find the average rate of change for f(x) = x2 − 3x − 10 from x = −5 to x = 10.

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x

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?