I have the net amount of $1874.00 after subtracting 20% of the gross. 
Hw do I figure the gross amount?

It comes out you to the equation 80% of gross is equal to the net.
so divide the net amount by .8 and you will get the gross.

thetinman is right, but i think you will learn more if you learn to
solve a problem like this algebraicly, rather than by feel.  Disect
the words to form an equation, then solve for the unknown.

What is the unknown we are trying to find? The gross, clearly. So
let's call the gross "X".

Now lets breakdown the rest:
I have the net amount of $1874.00 after subtracting 20% of the gross
So it says that we subtract 20% from X and get 1874, right?  That
translates to X - .20X = 1874.

If you can understand how to get that formula, the rest is just simple
arithmetic and algebra:
X-.20X = .8X = 1874
.8X = 1874
.8x /.8 = 1874 /.8
X = 2342.5