Explanation:
such questions you can answer faster by either directly looking it up on the internet (1 pound = ... ounces), or by using the conversion or scale function on your calculator (e.g. the Windows basic calculator app has this function).
so, we find :
1 pound = 16 ounces
so, now it is easy to find how many pounds of apples were bought : every "group" of 16 ounces is 1 pound. so, we need to find how many such "groups" are in 40.
40/16 = 5/2 = 2.5 pounds.