So basically what you wanna do is multiply across giving you 40/88 which you can simplify down to 5/11
Hope this helps :D
The mathematical property that allows 40 * (25 * 74) = (40 * 25) * 74 would be the Associative Property of Addition and Multiplication. This property means that no matter how the values of an expression are grouped together (or "associating" with each other), the end result will be the same, as long as the symbols are all either multiplication or addition symbols.
Hope that helped =)
Answer
$7.80
Explanation
He bought 4 for $5.20. Divide 5.20 by 4 to get the price for one pack. Then multiply $1.30 by 6 to find the price of 6 packages.