The product of two rational numbers is -9.if one of the number is -12. what is the other number?

-12x = -9 ;;; divide by -3
4x = 3 ;;; divide by 4
x = 3/4

Check:
-12 * 3/4 = -9

Done.

Or you divide directly by -12:

-12x = -9
x = -9 / -12 = -3*3 / -3*4 = -3/-3 * 3/4 = 1 * 3/4 = 3/4