To find the probability of drawing a blue marble, we need to determine the total number of marbles and the number of blue marbles in the bag.

The total number of marbles in the bag is the sum of the red, blue, and green marbles:

Total number of marbles = 5 red marbles + 3 blue marbles + 2 green marbles = 10 marbles

The number of blue marbles is given as 3.

To calculate the probability of drawing a blue marble, we divide the number of favorable outcomes (getting a blue marble) by the total number of possible outcomes (drawing any marble):

Probability of drawing a blue marble = Number of blue marbles / Total number of marbles = 3 / 10 = 0.3 or 30%

Therefore, the probability of drawing a blue marble from the bag is 0.3 or 30%.