Help would be much appreciated ​

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?

Which of the following pairs of functions are inverses of each other? o a. f(x)=x72+8 and 96-9 = 7/x+2) =8 o b. f(x)= 6(x - 2)+3 and g(x) - *#2-3 o c. $4) = 5(2)-3 and 90- 4*: 73 o d. f(x) = 6)-12 and 910 – +12

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?