Answer
$156r$
Work Step by Step
We start with the given expression: $(12\times r)\times13$
The commutative property of multiplication states that changing the order of the factors does not affect the product.
We use this property to rearrange the factors: $13\times(12\times r)$
The associative property of multiplication states that changing the grouping of the factors does not affect the product.
We use this property to rearrange the grouping: $(13\times12)\times r$
We use the order of operations to simplify:
We simplify inside the parentheses: $156\times r$
We multiply: $156r$
