If the number is N, 8 times the number is 8N.

The sum of the number and 9 is (N+9).

When 8 times the number is added to the sum of the number and 9, you have

This can be simplified to

9N + 9

And factored to

9(N+1)

The sum of the number and 9 is (N+9).

When 8 times the number is added to the sum of the number and 9, you have

**8N + N + 9**This can be simplified to

9N + 9

And factored to

9(N+1)