It makes it easier to work out if we get rid of the decimal point by multiplying top and bottom by a suitable power of 10. In this case 100 is a good choice because we have 2 places of decimals in the denominator.
720/5625=16/125. This can be written 16×8/1000 because 8×125=1000.
So we get 128/1000. To divide by 1000 we move the decimal point 3 places to the left in the numerator=0.128.