From a group of students, 28 students like rice, 23 students like dumplings, 16 students like both and 11 students do not like rice nor dumplings. How many students were interviewed?

The lengths of all sides of a triangle are integers when measured in decimeters. one of the sides has length of 1 dm and another of 3 dm. find the perimeter of the triangle.'

True or false: the graph of y=f(bx) is a horizontal compression of the graph y=f(x) if b< 1

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?