The number of red marbles is 4. The number of blue marbles is 3. The total number of marbles is 10 because 4+3+3 is 10. P(red) is 2/5 because there are 10 total marbles and there are 4 marbles which is equal to 4/10 marbles are red, and you simplify 4/10 to 2/5. P(blue) is 3/10 because there are 3 blue marbles out of 10 marbles.
