Question

5x - 7x -9 = -2x + 5v-9

Answer 1

4x+5v .    Im not too sure about your question.

Answer 2

I think you type the wrong equation but I can guess that v is x or maybe a space
but if v = space. The answer will be false.
so I'll put x instead of v
$5x - 7x - 9 = - 2x + 5x - 9 \\ (5x - 7x) - 9 = ( - 2x + 5x) - 9 \\ - 2x - 9 = 3x - 9 \\ 5x = 9 - 9 \\ 5x = 0 \\ x =0$
The answer is 0