If the C2 is referring to C^2 (c squared), then
C^2 = 6^2 = 6*6 = 36
Note how I replaced the "C" with 6, because C = 6
Squaring a number is the same as multiplying it by itself.
Once you know the value of C^2, you divide it over the value for d, which is 3
So,
(C^2)/d = (36)/3 = 12
The final answer is 12
