You can set up a proportion since ratios are also fractions we can write the ratio like this 1/30. We know then for the next one 2/x. Because we want to know the actual distance and the proportion is map/actual, so these are equal.
1/30=2/x
Cross multiply
1x=60
x=60
The actual distance is 60 kilometers.
We also can do it by multiplying 2x30=60.