the probability she draws a red marble is $\frac{5}{12}.$
since there's no replacement, we now have a pool of 11 marbles to pick from. the chance of picking a blue marble from this is $\frac{4}{11}.$
multiplying the two fractions, we have $\frac{5 \cdot 4}{12 \cdot 11} = \frac{20}{132} = \boxed{\frac{5}{33}}$
please confirm if this is wrong or not as my alcumus rating for counting and probability is very low
if i get this problem right, it will be very lucky for both you and me