The answer is 2:1 because at first your ratio would be 18:9 but if you divide that by 9 (for simplifying purposes) than its 2:1
The probability of Event A is 5/10 which simplifies to 1/2.
The probability of Event B is 3/9 which simplifies to 1/3.
Because it says "and" we need to multiply them which gives us 1/2*1/3=1/6
