how to slove 2x+5x=7x
how to slove 2x+5x=7x
As you already know,
2x + 5x = 7x
7x = 7x
Whenever the answer to a solution is an identity (the same thing is written on both sides of the equal sign), the solution is all real numbers (unless there are numbers outside the domain, which is probably not a concent at this level of Algebra.
The solution is all real numbers.
Comments
In fact, the solution is ALL numbers, real or not, and even non-numbers (such as matrices) in any class that honors the identity property. But as you say, probably not a concern for an Algebra-level class.