Barbra has a coupon for 5% off of the cost of her dinner, She tips the waiter 20% of the discounted priice of her dinner, and pays a total (discounted dinner price + tip) of $18.24, how much did her dinner cost before the discount?
Let x = regular cost of dinner.
x - .05x + .20(x-.05x) = $18.24
Solve for x.