A teacher bought 120 pencils. The pencils come 15 to a package. How many packages, p, of pencils did the teacher buy?

Since they give you the unknown "p" I'm assuming that you need to write out an equation and then solve ... If we have 120 pencils and they are packaged into groups of 15, then we are dividing.

p = 120/15

p = 8

The teacher has 8 packages of pencils

He has 8 packages because 15 x 8 = 120