When you need to divide by a fraction, the first thing you do is invert the fraction and use it to multiply.
(7/12) / (14/15) = (7/12) * (15/14)
Multiply the two numerators, and multiply the two denominators
(7 * 15) / (12 * 14)
Simplify where possible: divide the 7 by 14, giving (1 * 15) / (12 * 2) (7/14 is 1/2)
For the next step, visualize this: (15 is 3 * 5; 12 is 3 * 4) so we have (1 * 3 * 5) / (3 * 4 * 2)
Divide both the 15 and the 12 by 3: (1 * 5) / (4 * 2) (we have divided the 3 in the numerator by the 3 in the denominator)
Perform the mulitplications: 5 / 8
If you have not been told to give the decimal equivalent, that is your answer. I'm sure, though, that the fraction is the answer that you are looking for.