PROBLEM: "Write a mathematical expression which corresponds to x time y minus a times b times c." So let's just think this through: "x times y." Well I could write that – I could either write that as x × y, or I could just write that as xy. And from that, I'm going to subtract a times b times c. So: minus a times ... And I could write it a [asterisk] b [asterisk] c. I could write it like that. Or I could just write -abc. And you can see how it's being interpreted by the computer right over here. It understands that I'm saying x times y minus a times b times c (or xy - abc). And I'm done.