Which property of arithmetic justifies rewriting the expression $(18 + 45) + 5$ as $18 + (45 + 5)$?

Commutative Property of Addition

Associative Property of Addition

Which of the following statements correctly describes the relationship between number sets?

Every rational number is an integer.

Every whole number is a natural number.

Every integer is a rational number.

Rational numbers cannot be negative.

True, because $-9$ can be written as the fraction $\frac{-9}{1}$.

False, because rational numbers cannot be negative.

False, because $-9$ is an integer, not a fraction.

True, because all negative numbers are rational.