c) A division fact of $a\xf7b=c$ is equivalent to the division fact $a\xf7c=b$.

Therefore $-8.58\xf7\u25fb=3.9$ is equivalent to the division fact $-8.58\xf73.9=\square \u25fb$.

Since $-8.58\xf73.9=-2.2$, then $-8.58\xf7-2.2=3.9.$

d) A multiplication fact of $a\times b=ca\times b=c$ is equivalent to the division fact $b=c\xf7a$.

Therefore $-3.2\times \u25fb=24$ is equivalent to the division fact $\u25fb=24\xf7(-3.2)\u25fb$.

Since $24\xf7(-3.2)=-7.524\xf7(-3.2)=-7.5$, then $-3.2\times -7.5=24.$