the question is as follows:

For all numbers x and y, let the operation ■ be defined by x ■ y = xy-y. If a and b are positive integers, which of the following can be equal to zero?

I. a■b

II. (a+b)■b

III. a■(a+b)

does one distribute choices II and III to a■b + b■b and a■a + a■b respectively? How does that help?

There is just something about the use of symbols that has not registered yet. Thanks.