I need help solving this equation. Thank You

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Marked as Best Answer

Hi again Pj;

12x+9-4x-4=3x-7-x+30

Let's combine like terms on both sides...

(12x-4x)+(9-4)=(3x-x)+(-7+30)

8x+5=2x+23

Let's isolate x...

Let's subtract 5 from both sides...

-5+8x+5=2x+23-5

8x=2x+18

Let's subtract 2x from both sides...

-2x+8x=2x+18-2x

6x=18

Let's divide both sides by 6...

(6x)/6=18/6

x=3

Let's check our results in the original equation...

12x+9-4x-4=3x-7-x+30

Let's substitute x with 3...

[12(3)]+9-[4(3)]-4=[3(3)]-7-(3)+30

36+9-12-4=9-7-3+30

45-16=2+27

29=29

It works!

Joshua D. | Algebra Teacher Algebra Teacher

PJ,

This equation isn't too bad. Just a couple steps and I bet you'll recognize what to do quickly.

12x+9-4x-4 = 3x-7-x+30

Step 1) Combine like terms

*If I think of the equation as having a left side and a right side (split by the = sign), I'm going to combine the similar terms on the left and right.

LEFT: 12x+9-4x-4 ---->8x+5 (I did 12x-4x and 9-4)

RIGHT: 3x-7-x+30 -----> 2x+23 (3x-1x and -7+30)

So now we have 8x+5 = 2x+23 (The variable is on both sides of the = sign) (Not good)

Step 2) Eliminate one of the variables

8x+5 = 2x+23 (I'm going to subtract 2x from both sides to get rid of one variable

-2x -2x

6x+5 = 23 (Now it's just a two-step equation, easy!)

-5 -5

6x=18 -----> x=3

**Don't forget to check!

12(3)+9-4(3)-4 = 3(3)-7-3+30

29 = 29 (Correct!)

12x + 9 - 4x - 4 = 3x - 7 - x + 30

8x + 5 = 2x + 23

6x = 18

x = 18/6

x = 3

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