I think the question for task #2 is incorrect, it is asking for a constant when it should be asking for a variable. Yes?

task 2 states: Next create a constant called price and assign it the value 9.99.

you define constants using the let keyword

let someConstant = someValue

so you would use:

let title = "A Dance with Dragons"
let price = 9.99

Constant values cannot change after they are set. using a constant in this instance is correct if we dont want the price to ever change. In this case the we want the price of A Dance With Dragons to always be 9.99, so it makes sense to use a constant

It does not matter that price is a double. any data type can be a constant and any data type can be a var. The difference is that the values of vars can change, and the value of constants cannot.

for more information on constants and variables see the Swift eBook which explains the main difference between constants and variables:

Constants and variables associate a name (such as maximumNumberOfLoginAttempts or welcomeMessage) with a value of a particular type (such as the number 10 or the string "Hello"). The value of a constant cannot be changed once it is set, whereas a variable can be set to a different value in the future.

thank you! when I was checking the work, it stated it should be a "double" but //double wasn't letting y work get approved - I tried it in xCode and it seems fine - prob user error :)