\( \definecolor{colordef}{RGB}{249,49,84} \definecolor{colorprop}{RGB}{18,102,241} \)
You start a stamp collection with \(12\) stamps. Each month, you add \(4\) new stamps to your collection.
Let \(u_n\) be the number of stamps you have after \(n\) months.
  1. Find the explicit formula for \(u_n\).
    \(u_n=\)
  2. How many stamps will you have after \(15\) months?
    stamps