Problem with helloworld in gtk+

I just bought the book "Foundations of GTK+ Development" by Andrew Krause but am stuck at the first example!

[user@localhost gtkbook]$ gcc -Wall -g helloworld.c -o helloworld `pkg-config --cflags gtk+-2.0` \ `pkg-config --libs gtk+-2.0`
gives
gcc: -lgtk-x11-2.0: No such file or directory
The example /usr/bin/gtk-demo works, built in by Acer I think.
The command [user@localhost gtkbook]$ gcc -c -Wall -g helloworld.c -o helloworld `pkg-config --cflags gtk+-2.0`
gives
[user@localhost gtkbook]$
so works and gives the helloworld.o file OK so it must be the linker?
I have installed using add/remove programs the likely looking gtk things.
I have these in my /usr/lib directory:
libgtk-x11-2.0.so
libgtk-x11-2.0.so.0
libgtk-x11-2.0.so.0.1200.8
Please, what is wrong or missing?

 

Sorry to have bothered you. After hours of searching through linker options, .so files, etc, I found the problem is the "\" in the command line. Without it the gcc does the job. It is in the book !!!!! why I don't know?
George.