"Show your work" is not needed in presentations
But the workplace is different. As professionals, our presentations are not an attempt by our bosses to check if we know our job. They do that evaluation before they ever hire us. If we couldn’t do the work, we wouldn’t get the job, it’s as simple as that.
Your presentations are to present the result of your work in a way that enables others to use the information to make decisions or use the knowledge to be more effective and efficient in their own work. If you show all the background and data, you lose the audience because it is overwhelming. There is so much coming at them, they don’t know what the most important point is. And they give up trying to figure it out, or, even worse, come to a different conclusion than the one you wanted them to reach.
Instead, present only the conclusions from your work and in a way that clearly shows the meaning of the analysis to this audience. Always be thinking about what the audience really wants to know from you. They don’t want to know all the work you did, they only want to know how the conclusion will impact them. Feel free to have backup or Appendix slides that contain more details in case someone wants to see the details, but don’t include those slides in the main part of your presentation.