Ok, so 6*6 is 36, which means that there are 36 options between the two cubes. Since only 6 of these options have the sum of 7 (1/6, 2/5, 3/4, 4/3, 5/2, 6/1), which means that the probability of rolling the cubes to get the sum of 7 is 1/6, or 6/36.
So, the answer you are looking for is 1/6.