The matrix below represents a system of equations.
1 1 -2 1
2 -3 1 -2
2 2 -4 2
Which of the following describes the solution to this system of equations?
A dependent
B inconsistent
C independent
D unique

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?