Look at it this way. After statement 2, you have 101 remaining. using the two remaining number combinations, how can you get 101:
100 + 1
60 + 41
30 + 71
But.. Statement 1 states the max number is 60, we use 60 as the max number to see how small the fouth number could possibly be. Since the fourth number is 101-60=41, we know that the 3rd and 4th number must be above 30.