What 2 numbers whose sum is 105.7 the numbers are 19, 85.2, 533, 571, 88.2, 525, 20, 17.5, 400, 261, 20.5 ,125, 7, 23, 901, 30

To make it quickly we can consider only those numbers which will give us a decimal of xxx.7. There are only a few numbers like this: 85.2, 88.2, 20.5.
 
I tried adding 85.2 to 17.5 and it gave me 102.5 - it was close but not close enough :)

So I picked 85.2 + 20.5 = 105.7 and voila :)

10120202020000000304040404