Store A sells boxes of rice for $2.50 each. Store B sells rice by the pound for $2.50 per pound.

The cost of an amount of rice at either store can be modeled by the function c(n) = 2.5n, where n is the number of boxes for Store A and n is the number of pounds of rice for Store B.

The domain of c(n) = 2.5n is all the real numbers.

For each store, drag the restriction needed on values of n for c(n) to model each situation.

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?