Let normal price=y Let modified price=x 12% off=88% of normal price, without tax=.88*x without tax. Tax=additional 3%=1.03*price=1.03*.88*x=.9064x Since .9064x is our final modified price, the equation is y=.9064x y=1.03* .88* x ^ Sales tax multiplier ^12% off sale ^ original price