Asquare and a regular heptagon are coplanar and share a common side $\overline{ad}$, as shown. what is the degree measure of angle $bac$? express your answer as a common fraction.

You can find the constant of proportionality by finding the ratio of

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?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)