Which property of equality is x + (3x + 20) = 180?

Question

 I am looking for the properties of the following equations:

 

1. x + (3x + 20) = 180

 

2. 4x = 160

 

3. x = 40

 

Any help is very appreciated! :)

Answer 1

x + (3x + 20) = 180  <---- given

 

(x+3x) + 20 = 180 <--- associative

 

4x + 20 = 180 <---- combines like terms

 

4x = 180 - 20 = 160<--- subtracts 20 from both sides

 

x = 160/4 = 40 <--- divides both sides by 4