HELP PLZZZ which equation represent the model? 1. s+12+30

2.s+4+= 30

3. 3s +4= 30

4. 3(s+4) =30

the model is

3 boxes of s+4

30

Find the midpoint m of z1=(8+5i) and z2=(12+3i)

Use the elimination method to solve the systems of equations. choose the correct ordered pair. 7x+4y=39

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?