well it depends what 'v' stands for
well all you need to do is replace the v with the number it stands for. For example if v=2 then the expression would be 4.2(2) - 5 - 6.5(2)
Then you use the order of operations. first you multiply
8.4 - 5 - 13
then you subtract from left to right
8.4 - 5 = 3.4
3.4 - 13 = -13 - 3.4 = -9.4
So IF v=2 (I used 2 as an example, V might not = 2 in your case) then the
answer will be -9.4
I hope this helped you :3