Solve One-Step Equations: x + 7 = 19 (6th Grade)

What is it?

An equation says that two sides are equal, like a balanced scale. In x + 7 = 19, the letter x stands for a number we do not know yet. To solve it, get x alone on one side by undoing what was done to it. Adding 7 is undone by subtracting 7. Whatever you do to one side, do the same to the other, so the scale stays balanced. Then check the answer by putting it back in.

Step by step: x + 7 = 19

1. Read x + 7 = 19 as: some number plus 7 makes 19.
2. x has 7 added to it. Undo that by subtracting 7.
3. Do the same to both sides to keep them equal: x + 7 − 7 = 19 − 7.
4. On the left, +7 and −7 cancel, leaving x. On the right, 19 − 7 = 12.
5. So x = 12.
6. Check: put 12 back in. 12 + 7 = 19, and that is true.

Common mistakes

• Subtracting from only one side. Both sides must change in the same way.
• Using the wrong inverse, like adding 7 to 19 to get 26. Undo addition with subtraction.
• Skipping the check. Putting your answer back in the equation takes seconds and catches mistakes.

Your turn

Here is a problem to try. Pause and let your child work it out before you check.

Solve 4x = 28.

Answer: x = 7. 4x means 4 times x, so undo it by dividing both sides by 4: 28 ÷ 4 = 7. Check: 4 × 7 = 28.

Practice at home

Hide a number in a cup, like a bag of x marbles. Say "x plus 7 makes 19" and have your child find x, then check by adding 7 back. Switch roles, and mix in multiplying ones like "3 times x is 18". Always ask them to explain which operation they are undoing.