Answer:
Colleen
Step-by-step explanation:
It says that:
Gabby spent less than Mark. Therefore Gabby<Mark
Mark spent less money than Layla. Therefore Mark<Layla and Gabby<Mark<Layla
Layla spent less money than Colleen, so Layla<Colleen and Gabby<Mark<Layla<Colleen.
Colleen spent the most money.
