Using the fact family of $4$4, $4$4, and $8$8.
$+$+ | $=$= | |||
$4$4 | $+$+ | $4$4 | $=$= | $8$8 |
What is $8-4$8−4?
Using the fact family of $9$9, $9$9, and $18$18:
We are interested in the fact family of $5$5, $5$5, and $10$10:
Using the fact family of $2$2, $5$5, and $7$7.