Answer: Although I am not 100% sure, I would think the domain 2<x<6 (x being the domain and the point must be on the line) although for these signs they would be "or equal" to. The range would be 6<y<18 (y being the range and once again the point must be on the line) with "or equal" to signs.
Explanation:
This is because since there are no concrete points, other than the two ends of this (piecewise?) function, you would have to set the domain to be all x values that fall on this line, hence x being between 2 and 6. The same happens for y, in which, since there are no points plotted, the range is all the y values on the line. Once again, I am not absolutely sure about this, but it seems logical, at least to me.