Grade 6

Solve for n

Equations. Part of below zero and beyond.

Solve for n

Equations · Alberta Grade 6 · maddyhelps.com

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An equation is a balance: whatever is done to one side is done to the other. Find n, then check it by putting it back in. The last two take two steps — undo the adding or subtracting first.

n + 8 = 21
n =

n − 6 = 14
n =

5 × n = 45
n =

n ÷ 4 = 7
n =

2 × n + 3 = 17
n =

3 × n − 4 = 20
n =

Tickets cost $7 each, plus a $5 booking fee. Mia paid $40. Write an equation and find how many tickets she bought.

Sam says n + 8 = 21 means n = 29. Check his answer. What went wrong?

For the grown-up

Solve for n

n + 8 = 21: n = 13, n − 6 = 14: n = 20, 5 × n = 45: n = 9, n ÷ 4 = 7: n = 28, 2 × n + 3 = 17: n = 7, 3 × n − 4 = 20: n = 8. Tickets: 7 × t + 5 = 40, so t = 5. Sam: 29 + 8 = 37, not 21. He added 8 instead of taking it away; n = 13.

Checking by substitution is the habit to build. It turns every equation into one with a known answer, and it catches Sam's mistake — doing the operation instead of undoing it — every time.

Why this matters is on the below zero and beyond page. More sheets