Two researchers are studying the decline of elephant populations. In one study, a population of 1,568 elephants is expected to decrease at a rate of 50 elephants per year. In a second study, the population of a group of 1,634 elephants is expected to decrease at a rate of 72 elephants per year. After how many years will the two populations be the same?

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?