x+(x+2)+(x+4)=77

We could remove the parentheses because they have no function in this equation. 

 

x + x + 2 + x + 4 = 77

 

Then we can combine like terms

 

3x + 6 + 77

 

Subtract 6 from both sides

 

3x = 71

 

x = 71/3