Standard The grocery store clerk put only packages of flour tortillas and packages of corn tortillas on the shelf. The ratio of the number of
packages of flour tortillas to the total number of packages on the shelf was 9 to 21.
Which number could be the number of packages of corn tortillas the clerk put on the shelf?

b. 18

Step-by-step explanation:

From the information, we know that the clerk  put only packages of flour tortillas and packages of corn tortillas and that the ratio of the number of packages of corn tortillas to the total number of packages on the shelf was 7 to 16. This means that the rest of the packages which have a ratio of 9 to 16 are of flour tortillas. From this and the options given, you can infer that the number of packages of flour tortillas that the clerk could have put on the shelf is 18 because it is the only number that is a multiple of 9.