Please help! I'm terrible at two-column proofs!
Fill-in-the-blanks of the following two-column proof:
Given: QS = 42
Prove: x = 13

Statements Reasons
QS = 42 1. Given

QR + RX = QS 2. Segment Addition Postulate

(x + 3) + 2x = 42 3.

3x + 3 = 42 4.

3x = 39 5.

X = 13 6. Division Property of Equality

Question

Please help! I'm terrible at two-column proofs!
Fill-in-the-blanks of the following two-column proof:
Given: QS = 42
Prove: x = 13

Statements	      Reasons
QS = 42	              1.  Given

QR + RX = QS	      2. Segment Addition Postulate

(x + 3) + 2x = 42  3. 	 

3x + 3 = 42	      4.

3x = 39	              5.

X = 13	              6.  Division Property of Equality

anonymous · Answer

|dw:1421212427723:dw|

directrix · Answer

In going from step 2 to step 3, you replaced the segments by the lengths of them.

What is that called?

directrix · Answer

It is one of these. See attached.  @jak2299

anonymous · Answer

Substitution property right? @Directrix

directrix · Answer

@jak2299   Correct.

On reason 3 to 4, I'm not sure what reason your text uses.

Maybe Simplification (x + 2x = 3x)

Look in your book and see.

From reason 4 to 5, ask yourself:

What operation do you do to 3x + 3 = 42 to get
                                             3x       = 39
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