A bag contains 105 red and blue marbles. The ratio of red to blue marbles is 2:5. How many red marbles are in the bag?

30 red marbles

Step-by-step explanation:

If the ratio is 2 red marbles for every 5 blue marbles then you would add them together to find out how many marbles are in one group.

2+5=7

There are 7 marbles in each group.

Now we have to find out how many total groups there are by dividing the total amount of marbles by the amount in each group.

105÷7=15

There are 15 groups of 7 marbles.

Looking back at the ratio, we know that the 15 groups each have 2 red marbles and 5 blue marbles. So if there is 2 red marbles 15 times (2 marbles in 15 groups) we would multiply.

2×15=30

There are 30 red marbles.

I hope that makes sense.

7. d. 64

8. i. 32

9. c. 125

10. j. none of the above

11. d. 81

12. i. 216

13. e. none of the above

14. g. 240

15. e. none of the above

16. g. 32

17.   e. none of the above