I was in middle school in the mid-80s when I learned the Universe was something like 10-20 billion years old based on our estimates of the Hubble constant from the decade before. I was in high school in the late 80s and early 90s when we used the CBR measures to estimate 14 billion. I was in college when that was refined to 13.7 based on supernova data. That's been tweaked a bit here and there but mostly remained stable.