Final answer:
The fact family for 9, 10, and 90 consists of addition and subtraction equations: 9 + 10 = 19, 10 + 9 = 19, 90 - 10 = 80, 90 - 9 = 81.
Step-by-step explanation:
A fact family consists of three numbers that are related through addition and subtraction. To find the fact family for 9, 10, and 90, we can determine the corresponding addition and subtraction equations.
The addition equations for this fact family are 9 + 10 = 19 and 10 + 9 = 19. The subtraction equations are 90 - 10 = 80 and 90 - 9 = 81.
Therefore, the fact family for 9, 10, and 90 is:
9 + 10 = 19
10 + 9 = 19
90 - 10 = 80
90 - 9 = 81