Answer:
the percentage of red marbles in the bag is 30%.
Explanation:
To find the percentage of red marbles in the bag, we need to divide the number of red marbles by the total number of marbles and then multiply by 100:
Percentage of red marbles = (Number of red marbles / Total number of marbles) x 100
Number of red marbles = 12
Total number of marbles = 40
Percentage of red marbles = (12/40) x 100
= 0.3 x 100
= 30%
Therefore, the percentage of red marbles in the bag is 30%.