Kat's purchase before sales tax totaled 68 dollars The total including tax was 72.93 dollars What was the sales tax rate?
let y = the tax, in percent
68 + 68 x y/100 = 72.93 => subtract 68 from both sides:
68y / 100 = 4.93 => multiply both sides by 100 to eliminate
fractions:
68y = 493 => divide by 68 to isolate y:
y = 7.25%