Question 614950
The first thing you can do is to change the 7x -(-2x) to 7x+2x since subtracting a negative value is the same as adding a positive value.


{{{4x - 7x + 2x}}}


Now since they all the terms have x in common, you can factor that out:


={{{x(4 - 7 + 2)}}}


The constants can be added together (4 - 7 + 2 = -1) and then multiply the sum by the x that was factored out resulting in -x.


={{{-x}}}