More or less a quote from a puzzle...
Suppose the hundred's digit of a three digit number is greater than the 10's digit and greater than the units digit.

When the digits in this number are reversed, and the result is subtracted from the original number, the units digit of the difference is 4.

a) What is the difference between the 3 digit number and its reverse.

b) How many different 3 digit numbers meet the give conditions?

Please help me...