true or false

I would say true.....

 

here is an example

 

2x     - 3y    =12           and y = x-1   sub in y

2x  - 3 (x-1) = 12            without parens, the final derived  answer would be incorrect

 

You should use parentheses when substituting?    

 

It is better to not need parentheses and use them, than to need parentheses and not use them.