What number is half - way between 14 and 42

Which of the following expressions are equivalent ?

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.

If the endpoints of the diameter of a circle are (8, 6) and (2,0), what is the standard form equation of the circle? a) (x + 5)2 + (y + 3)2 = 18 (x + 5)2 + (y + 3)2 = 3.72 (x - 5)2 + (y - 3)2 = 18 d) (x - 5)2 + (y - 3)2 = 32