Which expression is equivalent to 13 - (-21)

Complete the equation of the line through (−10,3) and (−8,−8). use exact numbers.

Simplify (1/2)4th power a. (1/16) b.(1/8) c.(1/4)

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?