Six friends each put $250 into a single account that earns 5.5% annually. the interest earned is added to the account at the end of each year. the friends want to use the money in the account to go on a vacation after four years. the friends get together after most have finished college four years later. how much money is in the account?

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?