this is an aops prealgebra 2 problem (I'm taking the course rn and it was the first problem in week 1.) so I'll give @Choff a hint instead of the answer.
try writing 0.025% as a fraction. What do you get?
btw, @Melody is wrong...
Yes Kit, guest has a valid point....
I will give a hint:
\(0.025\% = \frac{0.025}{100}\)
Multiply top and bottom by 1000 by moving the point 3 places in the direction to make the number bigger.
Whole numbers really do have a point, it is at the end and it is invisable.
Now that you have 2 whole numbers, top and bottom, simplify.