To solve 3x = 12, you undo the multiplication by dividing — multiplying and dividing are inverses, just like in a fact family. Warm up multiplication facts and inverse thinking and these equations are quick.
Answer these 3, then press Show my path. No grade — this just points you to the right level.
1. If 3 × 4 = 12, which is also true?
2. What number makes 3 × □ = 15 true?
3. Check: does x = 4 make 2x = 8 true?
Multiplication and division are inverses — they undo each other. 3x means 3 times x. To find x, divide by 3. Then substitute back to check.
Your quick check picks one for you, but you can switch any time:
Level 0 Find the missing factor step by step.
A. What goes in the box? 2 × □ = 6
Undo ×2 by dividing: 6 ÷ 2 = 3.
B. What goes in the box? □ ÷ 2 = 4
Undo ÷2 by multiplying: 4 × 2 = 8.
C. Complete the fact family: 4 × 3 = 12, so 12 ÷ 3 = ___
Dividing by 3 undoes multiplying by 3: 12 ÷ 3 = 4.
Level 1 Pick the inverse, then solve.
A. To undo × 4, what do you do to both sides?
Division undoes multiplication — they are inverses.
B. Solve: 4x = 12. What is x?
12 ÷ 4 = 3. Check: 4 × 3 = 12. ✓
Level 2 Solve and check by substituting.
A. Solve: x ÷ 3 = 5. What is x?
Undo ÷3 by multiplying: 5 × 3 = 15. Check: 15 ÷ 3 = 5. ✓
B. Solve: 18 = 6x. What is x?
18 ÷ 6 = 3. Check: 6 × 3 = 18. ✓
1. Solve: 5x = 20. What is x?
20 ÷ 5 = 4. Check: 5 × 4 = 20. ✓
2. Which step solves x ÷ 2 = 6?
Multiplying by 2 undoes dividing by 2: x = 6 × 2 = 12.
You've practiced exactly what Lesson 7-3 uses. Time to dive in.
Start Lesson 7-3 →