4 1/2 + 2 1/4 =? Can you tell me the answer

The graph of y = ax^2 + bx + c is a parabola that opens up and has a vertex at (0, 5). what is the solution set of the related equation 0 = ax%2 + bx + c?

Afrequency table of grades has five classes (a, b, c, d, f) with frequencies of 3, 13, 14, 5, and 3 respectively. using percentages, what are the relative frequencies of the five classes?

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?