Solve (x − 4)/3 = 5 (Step by Step)

How to solve the two-step equation (x − 4)/3 = 5, where x − 4 is divided by 3, with every step explained and a quick check of the answer.

Here 4 is taken away from x first, and then the whole thing is divided by 3. Undo them in reverse order: undo the divide by 3 by multiplying by 3, then add the 4 back.

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Step-by-step solution

Solve (x − 4)/3 = 5

Start with the equation: (x − 4)/3 = 5.
Multiply both sides by 3 to undo the ÷ 3: ((x − 4)/3) × 3 = 5 × 3, so x − 4 = 15.
Add 4 to both sides to undo the − 4: x − 4 + 4 = 15 + 4, so x = 19.
Check your answer: put x = 19 back in. (19 − 4)/3 = 15/3 = 5. Both sides match, so x = 19 is correct. ✓

Answer: x = 19

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Frequently asked questions

Why multiply by 3 first?

The brackets mean the whole x − 4 is divided by 3. Dividing happened last, so it is undone first: multiply both sides by 3 to get x − 4 = 15.

Why add 4 instead of subtracting it?

The equation takes 4 away from x. Adding 4 undoes that, so the − 4 and + 4 cancel and leave x by itself.

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