The sum of the digits of a two-digit number is subtracted from the number. How two-digit numbers can be formed so that the digit in the unit place of the resulting number many such 6?

Let the number be 10X + Y, (Y is in unit place and X is in the tenth place) 

So the sum of the digits will be X + Y if the sum of the digits subtracted from the number than the result will be 10X + Y - (X + Y) = 9X

So the number resulting will be always the product of 9 so if its need to have 6 in unit place

So the value of X must be 4 as e result it will be $9 \times 4 = 36$ here 6 in the unit place so all the two digit number which has 4 in tenth places will be the number

 So total such number will be 10 (40, 41, 42, 43, 44, 45, 46, 47, 48, 49) (ans.)