Hey there! I'm happy to help!
If we have 6 red marbles and 4 blue marbles, we have 10 total marbles.
First, we have the probability that a marble we draw is red, which is 6/10. This simplifies to 3/5.
If this happens, there are only 5 red marbles left and 9 total ones. So, the probability of drawing a red one again is 5/9.
We multiply these two probabilities together to see the probability of them both happening.
[tex]\frac{3}{5} *\frac {5}{9}= \frac{1}{3}[/tex]
The probability that both marbles are red is 1/3.
Have a wonderful day! :D