Tosha and her 3 friends Went to the movies. They
each got a ticket to the
movie and a drink. Two of
them got popcorn, and the
other two got a box of
candy. Write an expression
for how much the friends
spent at the movies.

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?