Commutative and Associative Properties

Solution to Example 7.6

Notice that $0.6+0.4$ is $1$, so the addition will be easier if we group as shown on the right.

Notice that $\frac{2}{5}⋅15$ is $6$. The multiplication will be easier if we group as shown on the right.

Try It 7.11

(a) $(1+0.7)+0.3=1+(0.7+0.3)$

(b) $(-9 \cdot 8) \cdot \frac{3}{4}=-9\left(8 \cdot \frac{3}{4}\right)$

Try It 7.12

(a) $(4+0.6)+0.4=4+(0.6+0.4)$

(b) $(-2 \cdot 12) \cdot \frac{5}{6}=-2\left(12 \cdot \frac{5}{6}\right)$