Total books sold = how many Jessica sold + how many Josh sold
256 = how many Jessica sold + how many Josh sold
Jessica sols 15 times more than Josh.
How many Josh sold = x
How many Jessica sold = 15x
256 = 15x + x
= 16x --> Divide both sides by 16
x = 16
Jessica sold 15 x 16 books = 240 books
Josh sold 1 x 16 books = 16 books