PuzzleM8 Learning games for families

Two-step equations

Solve 7x + 3 = 31

The aim is to get x on its own. Whatever we do to one side, we do to the other, so the equation stays balanced. This one takes 2 steps.

  1. 7x + 3 = 31The question.

  2. Step 1: Subtract 3 on both sides −3

    On the left, the x part has + 3 with it. Take 3 away from both sides to get rid of it.

    7x = 28

    On the left, the 3 cancels out.

    + 3 is undone by − 3.

  3. Step 2: Divide by 7 on both sides ÷7

    7x means 7 × x. Divide both sides by 7 to get x on its own.

    x = 4

    x is on its own. x = 4.

    Multiplying is undone by dividing.

Answer: x = 4

Check it

Put x = 4 back into the question. If both sides come to the same number, the answer is right.

Left side: 7x + 3 → 28 + 3 = 31

Right side: 31 → 31

✓ Both sides are 31, so x = 4 is right.

Now try it yourself

Solve this one in Algebra Balance. You choose each step, and it explains what happened, with hints if you get stuck.

Practise this in Algebra Balance

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