Error in CUDA Installation

good afternoon everybody

I have a question about cuda driver installation

i have installed cuda 7.5 over 5.5 via .deb files.

my step was :

  1. sudo dpkg -i cuda…deb
  2. sudo apt-get update
  3. sudo apt-get install build-essential
  4. sudo apt-get install cuda

but error like this :
The following packages have unmet dependencies:
cuda : Depends: cuda-7-5 (= 7.5-18) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

how to solve this problems? thanks