(1) It could be interpreted in many ways, but it doesn't matter how it is interpreted, because it would appear that the task is to find x. This can be achieved through by multiplying both sides by 100:
x/100=25/40, x=2500/40=125/2=62.5.
So this could be interpreted as 25/40 is 62.5%. Or it could be treated as a proportion: x is to 100 as 25 is to 40.
(2) The prevalence of 100 in the denominator makes it appear that this is a percentage problem (or a set of percentage problems), but it could still be interpreted as a proportion. Again, if the value of x is required, it doesn't matter which way the question is solved, because all interpretations will still give the same result for x.