What’s the distance between (-9, 5) and (-9, -1) please help

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?

Ithink i know it but i want to be sure so can you me out ?

Find the length of the radius of a circle with the center at -7+2i and a point in the circle at 33+11i