Answer :
84 blue marbles.
Steps:
1) Use the 3:7 ratio
2) Since there are 36 red marbles, you should know to multiply the ratio by 12.
3) Multiply 7 by 12 (7x12=84)
Steps:
1) Use the 3:7 ratio
2) Since there are 36 red marbles, you should know to multiply the ratio by 12.
3) Multiply 7 by 12 (7x12=84)