What is the difference between the largest 3 digit number and the smallest 3 digit number that can be formed using the digits 9, 8, 7 (without any repetition)?

The correct option is A 198
Different 3 digit numbers that can be formed with 9, 8, 7 without any repetitions are:

Number	Hundreds	Tens	Unit
987	9	8	7
978	9	7	8
897	8	9	7
879	8	7	9
798	7	9	8
789	7	8	9

From the above table comparing through place values it can be identified 987 is the largest and 789 is the smallest 3 digit number that can be formed
The difference between the these two numbers = 987 - 789
= 198