That's hard for Year 8.
They need to, for a start, have a really good grasp of fractions, especially division, and also knows that the line in the middle of the fraction also means division, which I find a lot of pupils can be shaky on. If she's not sure she's understood the lesson, then I'd double check that she knows, for example, that 1 over (5/8) means 1 divided by 5/8, and that she knows how to divide fractions by multiplying by the reciprocal. Similarly, can she divide 1/5 by 1/8 to get 8/5.
Then I'd want to make sure she has basics like knowing that something like 5/5 = 1 (again, sounds simple, but a surprising number of children don't see it as obvious!). And making sure that she can cancel when she has something like (8x18)/(3x2) - understanding the principle of being able to divide any of the top numbers by any of the bottom numbers, to simplify the problem without having to work out the multiplication. So realising that (5x5x5x5)/(5x5) would leave 5x5, etc.
Then they need to be very clear on what powers are - how to square and cube things, and that it's different that multiplying by 2 or 3 (another common mistake), and also that something to the power of 0 is equal to 1. That leads them to understanding the power rules - things like when you are multiplying numbers (of the same base) to a given power, you add the powers (i.e., 62 x 65 = 6^7 , because it means (6x6)x(6x6x6x6x6), which if you take the brackets out because it's all multiplication, is the same as 6x6x6x6x6x6x6).
And the same thing when you subtract, so 58/52 = 56, because it's (5x5x5x5x5x5x5x5)/(5x5), and you can cancel two of the 5s on the bottom with two of them on the top, which leaves 56 on top. That explains why you can just subtracting the powers, rather than having to write that out each time.
But if the top has a smaller power than the bottom, say 52/5*6, then it means (5x5)/(5x5x5x5x5x5), and if you cancel two of the 5s from the top with two of them on the bottom (making them both equal to one), you are left with 1/(5x5x5x5), or 1/54. And yet you can see that if you simply subtract the powers, you would get 5-4 (i.e., a negative power). Therefore 5-4 must be the same as 1/54.
Finally, you also have to know enough about multiplying fractions, to realise that if you want to put a fraction to a power, it doesn't matter if you think of it as, say (3/4)2 or 32/4^2, because when you multiply fractions, you are multiplying both the numerators and denominators, so both parts will end up to the appropriate power.
ONLY THEN would I want someone to attempt a question like this!
Yes, it's possible to just teach children rules about these - I see a lot of pupils who have been taught rules only: if the powers are divided you subtract and if is a negative number, you write 1 and then put the original number underneath, or you take the fraction and just write it upside down, and voila, correct answer. They have no real idea why, they don't really understand fractions/powers securely to begin with, and it's all just rote memory - which they then forget quite easily! They can often get the questions right in the homework because they just copy what they've done previously, but it's meaningless.
Sorry, this has been very long, but I hope it helps explain what sort of things she should have been learning before a question like this is given, and that can help you judge if it's suitable for the set or not. If they do know all the previous steps that I mentioned, then great, they are obviously teaching intensively, but thoroughly, and I know one local school that does really push maths in the lower years but seems to do it fairly well. I've also seen other schools, especially with lower sets, just try to teach rules with no understanding, to try and get them onto complicated work too early.