I'm not sure if your allowed to use scientific calculators or not, but if you are, you can add the fractions on those easily. I'll assume you are not allowed to though. What you first have to do is add all those numbers together to figure out the total number of gallons he is using. What I like to do with simple fractions like this is convert them to decimal. I have just committed them to memory, so I know that 1/4 is .25, 1/2 in .50, and 3/4 in .75. Now what I'm going to do is add up the whole numbers first. Those are 2 + 3 + 1, which equals 6. Now add up the decimals. It's like adding up whole numbers, but when you add a new "place" to the left, you put a decimal there. So, for example: .50 + .25 + .75 = 1.50. Why? Because You made a whole number when you added .25 and .75 together (you got one), but you still have a part, the .50 (or 1/2) "left" over. So now you have 1.50, and 6. Add those together. 1.50 + 6 = 7.50. Just add the 6 plus the 1, and then attach the .50 to the end. It's simple. Now you can convert it back to fractions if you want. You got 7.50, which is the same as 7 1/2. Say you don't want to convert the numbers to decimal and just add the fractions. That's easy, too. You can add 3/4 and 1/4 together easily, because their bottom numbers are the same. When bottom numbers (also known as denominators) are the same, you just add the TOP numbers together. 3/4 + 1/4 = 4/4, which lo and behold, makes a whole, which is 1. That makes adding the 1/2 to it easy...you can just throw it at the end of the 1, to make it 1 1/2. Now add that to the 6 as you did with the decimal. 6 + 1 + 1/2 = 7 1/2. That is how many gallons he is using throughout his house. Now that you know that, you just simply multiply 7 1/2 (or 7.50, as it is written in decimal) by 200, which is the cost per gallon. So what is 7 1/2 times 200? It is 1500, so your answer is C. I'm pretty sure I am right, although it is 3:06 AM, and even simple math problems can be trouble for me at this hour. Like I said though, I'm quite certain I am right.

It's another trick question. No one is going to live in a place long enough to paint a room where water costs $200 per gallon.