One week a certain van rental lot had a total of 20…

One week a certain van rental lot had a total of 20 vans, all of which were on the lot Monday morning. If 50 percent of the vans that were rented out during the week were returned to the lot on or before Saturday morning of that week, and if there were at least 12 trucks on the lot that Saturday morning, what is the greatest number of different vans that could have been rented out during the week?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #25805