Answer: 3:9, 1:3, 12:36
Step-by-step explanation: just multiply or divide your numerator and denominator by the same number. For the first one, I divided both 6 and 18 by 3, for the second I divided both 6 and 18 by 6, and for the last one I multiplied both 6 and 18 by 2. Hope this helps.