The total number of marbles = 6 + 5 + 2 = 13 marbles
Orange= 2 marbles
The probability of getting the first marble out of the hat is
2 / 13
The probability of getting the second marble out of the hat is
1 / 12 The total has been reduced by one and the number of orange marbles has been reduced by one.
2/13 * 1/12 = 2 / 156 = 1/78