Final answer:
Dave wrote the expression 8 x (6 x b) as (8 x 6) x b using the associative property of multiplication.
Step-by-step explanation:
Using the associative property of multiplication, Dave wrote the expression 8 x (6 x b) as (8 x 6) x b.
The associative property states that when multiplying three or more numbers, the grouping can be changed without changing the product.
In this case, Dave grouped 8 and 6 together first, and then multiplied the result by b.