Set Blueprint Variable Through C++ Code

I have the VehicleBluprintalt text from this project (GitHub - embiem/RoadSplineTutorial: Repo of my Unreal Engine 4 tutorial about transferring Blueprint to C++ (https://www.youtube.com/watch?v=ykrrXMQ3RqM)) that has a node to convert speed from units/sec to km/h. I would like to change the default value of 0.032 to 0.05 through code. I am fairly new to Unreal Engine and C++ in general.

Please assist. Thanks!!