On Wed, 02 Jan 2019 15:16:41 -0700, Chris L Peterson
wrote:
The diameter of the 4D sphere whose surface we're on is 13.8 billion
years. The diameter of the 3D sphere that defines the observable
universe (a section of the surface of the 4D sphere) is about 93
billion light years, which reflects its increase in size over 13.8
billion light travel years.

Then it has expanded at (90-13.8)/13.8 times the light speed.