to solve this, you have to put all of the integers with a common denominator - so first put them all in a fraction
so all the fractions are:
3/8, -5/16, -3/20, 2/4
now put them all in a common denominator form over 320
120/320, -100/320, -48/320, 160/320
so negative numbers are the least so we'll leave them for the end (descending)
the order will now be:
160/320, 120/320, -48/320, -100/320,
now put these in the form of the real integers:
2/4, 3/8, -3/20, -15/16