Each spin is independent of the other spin.
The probability of two independent events happening is the product of the individual probabilities.
6 gray; 2 blue; 8 total
p(gray) = 6/8 = 3/4
p(blue) = 2/8 = 1/4
p(blue then gray) = p(blue) * p(gray) = 1/4 * 3/4 = 3/16