I am stuck

Hi all, Can you please give me the explanation of this two questions: 1. How many integers n greater then 10 and less then 100 are these such that, if the digits of n are reversed, the resulting integer is n-9? A) 5 B) 6 C) 7 D) 8 E) 9 2. If x, y, and z are single-digit integers and 100(x) + 1,000(y...