1 part of 3 sections of a wall takes 1/4 of an hour, (.25 or 25% of an hour), (15 minutes is 1/4 of 60 minutes), so if it takes 15 minutes for one section to be painted & you have 3 sections,
you just have to do the opposite. Since the is n*-5/8 you want to use inverse operation and do -0.4 divided by -5/8 when you do that you end up with 0.01. So the value of n is 0.01
