If everything in the store is 40% off, then you can assume that the discount is .4*p, so the equation for the amount of discount would be d=.4p
The equation for the sale price of an item would be the starting price, p, minus the discount price, d. If we write this equation, we get S=p-d. Since we already solved for d, we can plug that into this new equation to get s=p-.4p. If the regular price is $85, then we can plug that in for p.
when it is plugged in, we get s=85,.4(85). Simplify this and you get s=85-34 or s=51. This means that the sale price would be $51
