Please answer this I will give brainliest and you get 20 points

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?

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?

Due to financial difficulties the owner of 4 skateboard stores is going to close 2 of his stores. based on the money earned at each store, which two stores should remain open?