Answer:
This is a function and it's because there's only one input for every output.
Step-by-step explanation:
Note: Although 5 and 1 both point to the same number this doesn't take away the validity of the function. :)
Ratio:
Red : Total
2 : 5
(x2) (x2)
4 : 10
Green : Total
3 : 10
Total of red and green marbles = 4 + 3 = 7
Blue marbles = 10 - 7 = 3
10 parts = 40 marbles
1 part = 40 ÷ 10 = 4
3 parts = 4 x 3 = 12
Answer: There are 12 blue marbles.