How many two digit whole numbers are increased by 18 when their digits are reversed?

To reverse by adding 18, the first digit must be smaller, and the second digit must be two greater.

Start with

13 - > 31

24 - > 42

35 - > 53

46 - > 64

57 - > 75

68 - >86

79 - > 97

That should be all together 7 two digit whole numbers.