How to find nth term in a sequence without the sequence being constant? Formula doesn't work!!!

What is the perimeter of square abcd? units units 28 units 37 units

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?

If two angles of a triangle have equal measures and the third angle measures 90°, what are the angle measures of the triangle? a. 60°, 60°, 60° b. 45°, 90°, 90° c. 30°, 30°, 90° d. 45°, 45°, 90°