How I solve these is to divide the sale price by the current percentage of the price. Since is is only 80% of the original price, I would divide $75 by 80, which will give you the amount that is equal to 1%. then multiply that number by 100 and it will give you the full cost of the item.
$75 / 80% = 0.9375
0.9375 x 100 = $90.75
