Plrase help ya'll I am going to rip my hair out i'm overthinking

For what value of jn is mn parallel to kl

Which is the completely factored from of xy^3-x^3y

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?