human
Andrea needs 45 rhinestones to finish an art project. She bought a third of what she needed and found a fifth of what she needed in her supplies. How many rhinestones does she still need?
assistant
How many rhinestones did Andrea buy? ** Andrea bought 45 / 3 = <<45/3=15>>15 rhinestones.
How many rhinestones did Andrea find? ** She found 45 / 5 = <<45/5=9>>9 rhinestones in her supplies.
How many rhinestones does Andrea still need? ** Thus, Andrea still needs 45 - 15 - 9 = <<45-15-9=21>>21 rhinestones.
#### 21