Please help! see question below :)

Rose bought a new hat when she was on vacation. the following formula describes the percent sales tax rose paid b=t-c/c

The anwser cause i do not understand just plez

Click an item in the list or group of pictures at the bottom of the problem and, holding the button down, drag it into the correct position in the answer box. release your mouse button when the item is place. if you change your mind, drag the item to the trashcan. click the trashcan to clear all your answers. find the lateral area for the prism. l.a. = 0123456789