Probability

Probability = 6/(14) * 5/13

= 3/7 * 5/13

=15/91

The total amount of marbles: $6+5+3=14$

The probability that your first pick is red: $\frac{6}{14}$

The likelihood that the second pick is red: $\frac{5}{13}$, remember you already picked a red one!

Multiply them together to get: $\frac{6}{14}\cdot\frac{5}{13}=\frac{30}{182}$, and just simplify that yourself to get the answer!

I hope this helped!