Question

Stan's statement:
Equation - 5+2(x+4)=10-5(x-3)
Step 1 - 5+2x+8=10-5x+15
Step 2 - 13+2x=25-5x
Step 3 - 13-3x=25
Step 4 - -3x=12
Step 5 - -3x/-3=12/-3
Step 6 - x=-4

Which statement about Stan's solution is true?
A. Stan's solution is correct.
B. Stan has a mistake in Step 1.
C. Stan has a mistake in Step 2.
D. Stan has a mistake in Step 3.

My work:
Equation - 5+2(x+4)=10-5(x-3)
5+2x+8=10+-5x+15
13+2x=25+-5x
+5x= +5x
13+7x=25
-13 =-13
7x/7=12/7
x=1 7/10

B. Stan has a mistake in Step 1.

Is this correct? Did I make a mistake in my work?

Answer 1

Are you using - to mean minus or just a dash?

In Equation - 5+2(x+4)=10-5(x-3), is the equation supposed to be
- 5+2(x+4)=10-5(x-3) OR 5+2(x+4)=10-5(x-3)?

It is dangerous to use dashes in mathematics.

Answer 2

I thought that Stan's equation is this: - 5+2(x+4)=10-5(x-3).
I got the same thing he did for his first step.

Answer 3

In your work, I think you lost the negative sign in front of the 5.

My work: Equation
- 5+2(x+4)=10-5(x-3)

5+2x+8=10+-5+15

Answer 4

Well, I don't usually use dashes, it is just hard for me to type math problems on a computer.
The equation is 5+2(x+4)=10-5(x-3).

Answer 5

I got this for the first step which is what Stan got:

5+2x+8=10-5x+15

5+2x+8=10+-5+15 yours

You left out the x on +-5 + 15 but I think you got what Stan did.

Answer 6

Do you think that this step Stan did is correct:

Step 3) 13-3x=25

Answer 7

Let's look at it:

Step 2)

13 +2x = 25 - 5x
+5x = + 5x
----------------------------

13 + 7x = 25

Answer 8

7x/7=12/7 x=1 7/10

12/7 = 1 5/7

Answer 9

Step 3 is where I think Stan made an error. What do you think:

Step 3: 13-3x=25

Answer 10

Because:
Step 2) 13+2x=25-5x

13 + 5x + 2x = 25
Step 3) 13+ 7x = 25

That is not what Stan got for Step 3.

Answer 11

No, Stan messed up Step 3. Step 1 and 2 in my work looked the same as Stan's. Stan subtracted 5 from 2x instead of adding 5 to 2x.

Answer 12

Thank you.

Answer 13

You are welcome.