An albatross is a large bird that can fly 400 km in eight hours at a constant speed. Using D for distance in kilometers and T for number of hours and equation that represents the situation is d=50t, write another equation that relates to t and d.

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?