I am trying to install **pgAdmin4** in **ubuntu 18.04**, but I get the following error:

```
The following packages have unmet dependencies:
 libpq-dev : Depends: libpq5 (= 10.6-0ubuntu0.18.04.1) but 11.2-1.pgdg16.04+1 is to be installed
E: Unable to correct problems, you have held broken packages.

```

I don't know how to solve this problem.

**EDIT**

I ran command `apt-cache policy libpq5`, and this is what I got:

```
libpq5:
  Installed: 11.2-1.pgdg16.04+1
  Candidate: 11.2-1.pgdg16.04+1
  Version table:
 *** 11.2-1.pgdg16.04+1 100
        100 /var/lib/dpkg/status
     10.6-0ubuntu0.18.04.1 500
        500 http://mx.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     10.3-1 500
        500 http://mx.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

```

But I don't know what to do with it.