For a question such as this, we most often simply use a calculator. However, I suppose that to do this by hand you would do as follows:
0.025 / 0.080
= 0.005 / 0.016
= 100 * (0.005 / 0.016)
= 5 / 16
The first step is a simplification. Both the numerator and denominator are divisible by 0.005. In the next step, we can multiply the numerator and denominator both by 100 to get whole numbers. Because we multiply each by the same number, we have not changed the value of the original fraction. This leaves us with 5 / 16.
