Rxplanation:
Number of Blue marbles = 9
Number of green marbles = 5
Number of yellow marbles = 12
Sum of all marbles = Number of Blue marbles + Number of green marbles + Number of yellow marbles
Sum of all marbles = 9 + 5 + 12
Sum of all marbles = 26
The ratio of yellow to blue to green:
Number of yellow marbles : Number of blue marbles : Number of green marbles
12 :