We solve this question using the least common multiple method
Find and list multiples of the liter the blue paint comes in the liters the yellow paint comes in. We find the first common multiple is found. This is the least common multiple.
Multiples of 9:
9, 18, 27, 36, 45, 54
Multiples of 12:
12, 24, 36, 48, 60
Therefore,
LCM(9, 12) = 36
Hence, the smallest amount of each paint color the store must have sold is 36 liters
I know it is between b and c i am not sure cause they are both similar in the way they look but if i had to choose maybe B sorry if its wrong, then its c