Answer:
21 red marbles
Explanation:
The ratio of red marbles to blue marbles = 3 : 4.
The proportion of red marbles in the bag
[tex]\begin{gathered} =\frac{3}{3+4} \\ =\frac{3}{7} \end{gathered}[/tex]If the total number of marbles in the bag = 49
Then, the number of marbles which are red
[tex]\begin{gathered} =\text{Proportion of red marbles x Total number of marbles} \\ =\frac{3}{7}\times49 \\ =3\times7 \\ =21 \end{gathered}[/tex]There are 21 red marbles in the bag.
