2(8+3)=2(8)+2(3)

is an example of which property

This is an example of the distributive property.

The example you provided is an example of the distributive property. The distributive property states that for any real numbers a, b, and c, the product of a and the sum of b and c is equal to the sum of the products of a and b, and a and c. In this case, 2 is multiplied by the sum of 8 and 3, which is equal to 2 multiplied by 8, plus 2 multiplied by 3.