On monday, it took helen 3 hours to do a page of science homework exercises. the next day she did the same number of exercises in 2 hours. if her average rate on monday was p exercises per hour what was her average rate the next day .in terms of p?

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?