ok so lets say how to find total total=how much you spent+(how much you spent times tax percent) you can use distributive proerty to undistribute the 'how much you spent' (like ba+ac=a(b+c)) to get total=how much you spent times (1+tax percent) so what you do is you know
how much you spent tax percent so
1. convert tax percent to deceimal 2. plug into foormula total cost=how much spent times (1+taxindecimalform)
