Aaron kept $12 000 in a bank account with an annual interest rate of 4%. After exactly 2 years, the bank chose Aaron as the winner for a prize money worth $5000. Aaron decided to invest all his savings and the prize money into a Trust Fund which offers a dividend of 4.5% per annum. When ( which year ) will all his investment value exceed $20 000?

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?