Studying for GRE: Linear Inequalities

[mecmath327]

I am reviewing Algebra for my GRE test. Here is one inequality problem that I do not understand...
I will provide the equation, the choices of answers, and their answer. I want to know HOW they solved it! Thank you!

Equation:

the letter x represents variable "x"
Equation writing in words: If 3x PLUS 4 is GREATER THAN Seventeen, 3x PLUS 7 is GREATER THAN

If 3x + 4 > 17, 3x + 7 >

Choices for Answers:

A.

13
-----
3

B.

22
-------
3

C. 14


D. 17

E. 20


Their answer:

3x + 7 = (3x + 4) + 3 > 17 + 3 = 20


I appreciate any feedback for this type of inequality problem!
Thank You

[stapel_eliz]

Equation writing in words: If 3x PLUS 4 is GREATER THAN Seventeen, 3x PLUS 7 is GREATER THAN

If 3x + 4 > 17, 3x + 7 >

Just add "3" to either side:

3x + 4 >  17
   + 3   + 3
------------
3x + 7 >  20

Hope that helps!

[mecmath327]

stapel_eliz,
THANK YOU!!
I reviewed what you posted, and looked back at the problem...NOW it makes sense!!
I see now, they (in the original equation) gave a partial answer.
It was a matter of knowing what step to do on the left side, thus you have to do the step on the right side!!
Thanks again!