If a sequence of numbers is paired with another so that the product is the same, $30$ is paired with?

Question

If each of the numbers $2, 3, 4, 6, 12, 18, 24, 36$, and $72$, is paired with a different one of the numbers $5, 10, 15, 20, 30, 60, 90, 120$, and $180$ so that the product stays the same, with which number is 30 paired?

Answer 1

if a is paired with c and if b is paired with d and if ab .there follows that since 30 is 5th which from the right must be paired with 12 which is 5th from the left .

Answer 2

Hint:

A big number in one list has to be paired with a small number in another list to keep the product to be the same.