Cuda installation error

Os version :ubuntu 18.04 LTS
i have downloaded deb local file of cuda tool kit. Followed instructions . But while running this code here on my terminal am getting an error. i need support to move further.

commandL]: sudo apt-get install cuda.
eroor getting,mj@mj-Inspiron-3543:~/Downloads$ sudo apt-get install cuda
Reading package lists… Done
Building dependency tree
Reading state information… Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
cuda : Depends: cuda-9-1 (>= 9.1.85) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.