Lana took one and a half times as long as jayden to finish a project. if lana took 15 days how long did jayden take

Let x = how many days Jayden took

Now, since Lana took 1.5 times as long as Jayden, however long Lana took would be 1.5x. We know that Lana took 15 hours, so 15 = 1.5x.
Solving the equation would give us,
x = 15/1.5
so, x = 10

Therefore, Jayden took 10 days.