What is the product?

Please look at the picture

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

What is the anwers for 9+2x=5x-3-x

Tim earns $120 plus $30 for each lawn he mows. write an iniqualityvto represent how many lawns he needs to mow to make more than $310