What is the greatest common factor of 42 and 84

a) 7
b) 21
c) 42
d) 84

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible

The vertices of a triangle are a(7.5), b(4,2), and c19. 2). what is

Need solving this 2nd limit problem.