For the set of Roman numerals X, XI the values are:

X = 10

XI = 11

10 < 11.

So, they are not arranged in descending order.

For the set of Roman numerals XLV, XXII, LI, XI:

XLV = 45 and LI = 51. 

45 < 51.

Therefore the set of Roman numerals XLV, XXII, LI, XI are not arranged in descending order.

For the set of Roman numerals XXXVIII, XLIX, LII, LXIV:

LII = 52 and LXIV = 64.

52 < 64

Therefore the set of Roman numerals XXXVIII, XLIX, LII, LXIV are not in descending order.

For the set of Roman numerals LXI, XLIV, XXXVIII, XXV the values are:

LXI = 50 + 10 + 1 = 61
XLIV = 40 + 4 = 44
XXXVIII = 10 + 10 + 10 + 5 + 3 =38
XXV = 10 + 10 + 5 = 25
Since, 61, 44, 38, 25 are in descending order so LXI, XLIV, XXXVIII, XXV are arranged in descending order.