Answer:
In the "9s count by" pattern, each row is related to the next row in the "10s count by" pattern by the following rule:
When you count by 9s, the ones digit in each number decreases by 1, while the tens digit increases by 1. This corresponds to counting by 10s in the next row.
Let's look at an example to illustrate this relationship:
9s count by: 9, 18, 27, 36, 45
10s count by: 10, 20, 30, 40, 50
In the first row, when counting by 9s, the ones digit decreases from 9 to 8, 7, 6, and 5. At the same time, the tens digit increases from 0 to 1, 2, 3, and 4.
In the second row, when counting by 10s, the ones digit remains the same (0), while the tens digit increases from 1 to 2, 3, 4, and 5.
Therefore, each number in the "9s count by" row is related to the next row in the "10s count by" pattern by a change in the ones and tens digit according to the rule mentioned above.