Is this problem right because i need to know

Sadly, the answer to your question is 'No'.  The work written under
the problem on the paper is not correct ... because you tried to do
too much !

You can't combine 'm' terms with 'n' terms or with plain numbers.
They all need to stay separate all the way to the end.

So, actually, your first written line is the answer . . .  7m - 35 + 3n

That's as far as you can go.  You can't combine these terms. Stop there !

Coma estrala meni prenias 2ft carn sharti

Step-by-step explanation:

grasia!!