What number must you add to complete the square x^2+2x=18

Which formula finds the probability that a point on the grid below will be in the blue area? p(blue) = total number of squares number of blue squares number of blue squares p(blue) = total number of squares number of blue squares p(blue) = number of white squares

When you answer this can you explain

Which expression gives you the distance between the points (5,1)and(9,-6)