Answer: 9
Step-by-step explanation: Root 18 can be broken down into root ( 9 times 2). 9 is a square root & can be taken out as its root. Root 18 equals 3 times root 2. Multiple both 12/root & 3 root 2 by root 2. Leaves 12 + 3 times 2 or 18. Now gotta take that root 2 we multiplied by back out. Break 18 into its parts, 9 times 2. Divide the 2 by root 2, gives you root 2. So 9 times root 2. Don't have to divide 9 as well, because they all the same type of operation, multiplication/division, no adding.