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Multi-Step Equations

A multi-step equation is a two-step equation with some cleanup in front. Equations like 4x+3+2x=214x + 3 + 2x = 21 or 3(2m+4)=303(2m + 4) = 30 look longer, but they aren't harder — the side with the variable just isn't simplified yet. Once you tidy it up, you're back to a two-step problem you already know how to finish.

So the whole strategy is: simplify first, solve second. Distribute any parentheses, combine any like terms, and only then start moving numbers across the equals sign.

The game plan

Step 1: distribute. If there are parentheses with a number in front, multiply it through every term inside.

Step 2: combine like terms. On each side separately, add up the variable terms and add up the plain numbers. 4x+3+2x4x + 3 + 2x becomes 6x+36x + 3.

Step 3: finish like a two-step equation. Move the constant to the other side, then divide by the coefficient.

Notice that steps 1 and 2 never touch the other side of the equation — you're just rewriting one side in a simpler form. Only in step 3 do you start doing matching moves to both sides.

Combining like terms first

Like terms have the exact same variable part: 4x4x and 2x2x are like terms, but 4x4x and 33 are not. In 9y54y=259y - 5 - 4y = 25, the like terms are 9y9y and 4y-4y — and the sign in front of a term travels with it, so they combine to 5y5y, not 13y13y.

Combining before solving matters because each side of the equation should be as short as possible before you start moving things. Trying to subtract terms across the equals sign while the side is still messy is where lost terms and sign errors come from.

Distributing without losing a term

In 3(2m+4)=303(2m + 4) = 30, the 33 multiplies both the 2m2m and the 44: 6m+12=306m + 12 = 30. The most common mistake is multiplying only the first term and writing 6m+46m + 4.

Also watch negatives: 2(x4)-2(x - 4) is 2x+8-2x + 8, because the 2-2 times 4-4 gives +8+8. Whenever you distribute a negative, every sign inside the parentheses flips.

Worked examples

Example 1: combine like terms, then solve

Solve 5x+4+2x=255x + 4 + 2x = 25.

Start with the equation5x+4+2x=255x + 4 + 2x = 25
Combine the like terms 5x5x and 2x2x7x+4=257x + 4 = 25
Subtract 44 from both sides7x=217x = 21
Divide both sides by 77x=3x = 3

Answer: x=3x = 3

Example 2: distribute, then solve

Solve 4(2k3)=204(2k - 3) = 20.

Start with the equation4(2k3)=204(2k - 3) = 20
Distribute the 44 to both terms8k12=208k - 12 = 20
Add 1212 to both sides8k=328k = 32
Divide both sides by 88k=4k = 4

Answer: k=4k = 4

Example 3: distribute and combine

Solve 2(3x1)+4x=182(3x - 1) + 4x = 18.

Start with the equation2(3x1)+4x=182(3x - 1) + 4x = 18
Distribute the 226x2+4x=186x - 2 + 4x = 18
Combine the like terms 6x6x and 4x4x10x2=1810x - 2 = 18
Add 22 to both sides10x=2010x = 20
Divide both sides by 1010x=2x = 2

Answer: x=2x = 2

Try one yourself

Common questions

How do I know what to do first?

Simplify before you solve. If there are parentheses, distribute. If there are like terms on one side, combine them. Only when each side is as simple as it can get do you start moving terms across the equals sign.

Can I combine terms from opposite sides of the equals sign?

Not directly. Combining like terms only works within one side. To deal with a term on the other side, add or subtract it from both sides — that's a solving move, not a simplifying move.

What if there's a negative in front of the parentheses?

Distribute it to every term and flip every sign inside: 2(x4)-2(x - 4) becomes 2x+8-2x + 8. Write the distributed line out fully before doing anything else — skipping it is the top source of errors.

How do I check my answer?

Plug it into the original equation, not the simplified one. If both sides match, you're right — and if they don't, the check tells you a mistake happened somewhere in your steps.

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