Two fiths of instrument in the marching band are bass ,one third are percussion, and the rest are woodwinds

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?

If f(x)= 3x+6 which of the following is the inverse of f(x)

Me! last question, and i'm stuck! write the algebraic expression that models the word phrase. the product of 2 divided by the number h and 8 more than the number k