Answer:
double plus two , two apart facts make ten extended strategy is used.
Step-by-step explanation:
Sum of 5 + 7 = 12 less two = 12; OR to make 10, I need to take 3 from the 5, add it to the 7 to make 10 and that leaves 2 from the 5. I add the 2 to the 10 I now have and that = 12.
