okay, i have to be honest, this equation is a little tricky because the use of "h" is kind of weird, using it twice to show...what exactly i am not too sure.
the answer:
The variable "t" is the amount of taxes she has to pay for repairing her cracked phone. "t" is shown as an extra amount of money to pay, and since it does not state that taxes were dependent on the amount of time it took to repair the phone, it must have been a fixed price. The amount of money it takes to repair the phone (tax not included) is shown to be dependent on time, though.