UPSC CAPF Assistant Commandant Model Paper 7

GIVEN:
A 3-digit number X74 is subtracted from a 4-digit number 1543 to get a 3-digit number YY9.
CALCULATION:
We need to check with the different values of X and see which value gives a result in which 1st two numbers are same.
Put X = 9:
1543 – 974 = 569
Put X = 8:
1543 – 874 = 669
Put X = 7:
1543 – 774 = 769
Put X = 6:
1543 – 674 = 869
Put X = 5:
1543 – 574 = 969
Further values need not to check as they will give a 4-digit number.
So, here it is evident that X = 8 and Y = 6
Now,
XXY + YYX = 886 + 668 = 1554