A3-9a2b + ab - 9b2

Can someone help please

In the diagram below, tan θ = sqrt 3. what is the value of m?

Divide. reduce the answer to lowest terms.5 2/3 ÷ 3 1/9

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?