In a 24 km race, during which each runner maintains a constant speed throughout, Alice crosses the finish line while Becky is still 8 km from finishing and Caitlin is 12 km from finishing. When Becky crosses the finish line, Caitlin still has $d$ kilometers to go. Find all possible values of $d$.
Think about a ratio between the distance Becky travels to the distance Caitlin travels.
Now, if Becky is 24, how many miles does Caitlin have left to go?