Hard riddle for ca's

Question - Take

9 from 6 i.e., 6-9

10 from 9 i.e., 9-10

50 from 40 i.e., 40-50

Next, rewrite the same in Roman Numerals

VI-IX

IX - X

XL - L

Next, convert each individual roman numerals into normal numerals

(5+1) - (1+ 10)= 6-11 = -5

(1+10) - (10) =11-10= 1

(10+50) - (50) =60-50= 10

Therfore the sum of -5, 1 and 10 is 6.

good but so close
this an alternative 
you can this question in this way 
i.e
SIX – 9 (IX)= S
9 (IX) – 10 (X) = I
40 (XL) – 50 (L)= X


SIX