Answer
Commutative Property of Multiplication
Work Step by Step
The Commutative Property of Multiplication states that when we multiply two numbers, order doesn’t matter. In case of 2x(3 + y) = (3 + y)2x, it wouldn't matter if we multiplied 2x by the expression (3 + y), or the other way around, so long as (3 + y) remains enclosed in the parenthesis. On the other hand, if we wanted to get rid of the parenthesis, we would have to use the Distributive Property:
2x(3 + y) = 2x $\times$ 3 + 2x $\times$ y
2x(3 + y) = 6x + 2xy