Jeff made 52.47 each day that he worked last week he spent $26.72 and still had $235.63 of his earnings left right and equation to find how many days Jeff worked last week.

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?