Add:

3mn,-5mn,8mn,-4mn

As all of them are having the same variables, we can see that they are having the same values.

But some of them are positive, while the others are negative so weea d the positive variables together first.

3mn+8mn=11mn

Now, we add the negative variables together.

(-5mn)+(-4mn)=-9mn

now we subtract 9mn from 11mn.

11mn-9mn=2mn

3mn+5mn

+-=-

=2mn+8mn=10mn

=10mn+(-4mn)=6mn

ans 6mn

3mn+( -5mn )+8mn+( -4mn)

3mn-5mn+8mn-4mn

-2mn+4mn

2mn ans

2mn guys use for brains

2mn

2mn

here the question is

add= 3mn,-5mn,8mn,-4mn

so ATQ we have,

=3mn+(-5mn)+8mn+(-4mn)

=3mn-5mn+8mn-4mn

=(3-5+8-4)mn

=(-2+4)mn

=2mn.....is d answer

2mn

3mn+(-5mn)+8mn+(-4mn)

First, we will add all the like expressions    [{3mn+8mn}+{(-5mn)+(-4mn)}]

                                                                             =11mn+(-9mn)

Now simply add the result                              = {11 + (-9) } mn

                                                                              = 2mn

Therefore, the result is 2mn.