Grade 8 · Math · Unit 6 of 11
Equations with Brackets
Solve ax = b, x ÷ a = b, ax + b = c and a(x + b) = c
What your child practises
Solving one-variable equations, including ones with brackets and negative numbers, checking by substitution, and spotting a common mistake with the distributive property.
Nunavut Curriculum approved guide: Alberta Mathematics K–9 (2007), Patterns and Relations · solving linear equations of the forms ax = b, x/a = b, ax + b = c and a(x + b) = c, and checking the solution
How we explain it
Children can open this short lesson before they practise.
- Undo brackets by dividing both sides, or by expanding.
- Do the same thing to both sides.
- Check by putting your answer back into the equation.
Example: Solve 2(x + 3) = 14. Divide both sides by 2: x + 3 = 7. Subtract 3: x = 4. Answer: x = 4
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Solve for x: x ÷ 8 = -3
answer box
-24
Hint: Multiply both sides by 8: x = -3 × 8 = -24.
Question 2
Solve for x: 2(x + 6) = 18
answer box
3
Hint: Divide both sides by 2: x + 6 = 9. Then subtract 6: x = 3. Check: 2(3 + 6) = 18.
Question 3
Which value of x makes 2x + 3 = 11 true?
- 4
- 3
- 5
- 6
4
Hint: Substitute each value. Only x = 4 gives 2 × 4 + 3 = 11.
Question 4
Solve for x: 6(x − 2) = 42
answer box
9
Hint: Divide both sides by 6: x − 2 = 7. Then add 2: x = 9. Check: 6(9 − 2) = 42.
Question 5
Solve for x: 2x − 2 = 8
answer box
5
Hint: Undo the subtraction first: 2x = 10. Then divide by 2: x = 5.
Question 6
Solve for x: 6x = 12
answer box
2
Hint: Divide both sides by 6: x = 12 ÷ 6 = 2.