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3x - 4 + 4x = 24

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3 Answers

3x-4+4x=24
First add all the (x)s together on one side of the equation.  So 3x +4x is 7x
 
Now the problem becomes 7x -4 = 24 or -4 +7x = 24
 
Either way is fine.
 
7x -4 = 24 you need to get the x alone on one side away from the number -4 so you add 4 to each side of the = sign.
 
If you add +4 to -4 you get 0 so the 4 goes away, but you can't add 4 to one side unless you add 4 to the other so the problem becomes:
 
7x = 28 (because you added the 4 to the left side of the = sign and the right side of the = sign)
 
7x = 28 (now to take the 7 off of the x, you need to do the same thing to each side, but this time you divide to make the x be by itself.) 7x divided by 7 = 1x so divide 28 by 7 too and you get 4.
 
x=4
 
Just remember what you do to one side (add, subtract, divide, etc.) to make the x alone, you need to do to whatever is on the other side.
 

Sophie:

Here we go: first always write out the equation. Always show all your work and you will make less mistakes.

3x - 4 + 4x = 24

Combine like variables and isolate any single numbers. Remember these equations are like a scale. What you do to one side, you do to the other. Always do the opposite of any operation on the left side and continue the same to the right, remember a scale or balance.

3x + 4x -4 = 24

7x -4 = 24

7x -4 + 4 = 24 + 4

7x  =  28

Isolate X

7x/7 =28/7

x = 4

THe first thing you do is figure out the parts that can be combined.  In this case you are able to add 3x and 4 x to get 7 x.

7x-4=24

Now you are able to isolate the "x" by adding 4 to each side : 7x-4+4=24+4

7x=28

The last part to figure out what x equals and to solve the equation is to divide both sides by 7:

7x/7=28/7

x=4