To solve x + 5 = 12, you undo the addition by subtracting — that's a fact family idea: adding and subtracting are inverses. Warm up fact families and substituting to check, and these equations come apart easily.
These are words you'll need to already know to follow this lesson — not the new words the lesson teaches. Review each one, its meaning, and the example so the new lesson makes sense from the start.
Level 1 To take one number away from another.
Example: 9 − 4 = 5 takes 4 away from 9.
Level 1 A number you add to another number.
Example: In 5 + 4 = 9, the addends are 5 and 4.
Level 1 A group of add and subtract facts that use the same numbers.
Example: 3 + 4 = 7 and 7 − 4 = 3 are in one family.
These check the skills you'll need for this lesson — not the new lesson itself. Answer all 3, then press Show my path. No grade — it just suggests where to start.
1. If 4 + 5 = 9, which is also true?
2. What number makes □ + 6 = 10 true?
3. Check: does x = 3 make x + 2 = 5 true?
Vocabulary previewed and basics checked. Time to start the lesson.
Start Lesson 7-2 →